US2865255A - Firearm with transversely movable barrel chamber - Google Patents

Description

R. MARSH Dec. 23, 1958 FIR'EARM wrm TRANsvERsELY MovABLE BARREL CHAMBER Filed Aug. s, 1955 7 Sheets-Sheet 1 BMZ hlw KO 5.54

R. MARSH Dec. 23, 1958 |lNvENToR Roger Marsh 3% @auf m '7'Sheets-Sheet 2 FIREARM WITH TRANSVERSELY MOVABLE BARREL CHAMBER Filed Aug. 3, 1955 l I l l I I l llJlllllll IIIA ATTORNEYS R. MARSH Dec. 23, 1958 FIREARM WITH TRANSVERSELY MOVABLE BARREL CHAMBER Filed Aug. 3, 1955 '7 Sheets-Sheet 3 lea /57 58 5?' INVENTOR Roger' Marsh B72 57,4%@ f m4-4 ATTORNEYS R` MARSH Dec. 23, 1958 FIREARM WITH TRANSVERSELY MOVABLE BARREL CHAMBER Filed Aug. 3, 1955 '7 Sheets-Sheet 4 INVENTR Roger Marsh BIQ?, maar ATTO N EYS Dec. 23, 1958 R. MARSH 2,865,255

FIREARM WITH TRANsvERsELY MovABLE BARREL CHAMBER Filed Aug. 5, 1955 7 sheets-sheet 5 A4 /5/ /aa /ab /56 /78 I a I @11" f7 INVENTOR l5 f 1"- Sai-; Roger Minsk .E5 z/e Bg Q, g ggg. 2 7 /98 47' ATTORNEYS Dec. 23, 1958 R. MARSH 2,865,255

FIREARM WITH TRANsvERsELY MovABLE BARREL CHAMBER Filed Aug. 3, 1955 '7 Sheets-Sheet 6 /23/ 254 (zzz 225 25711- 2 F17. E7 ZZ/ 2,34 44 Z5l\ ZZ 4Z 46 ZZ/a. 249

66 60 INVENTOR R. MARSH Dec. 23, 1958 FIREARM WITH TRANSVERSELY MOVABLE BARREL CHAMBER Filed Aug. 3, 1955 7 Sheets-Sheet '7 h Sv um,

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y wen n WMM INVENTOR Roger Marsh M5@ am ATTORNEYS 2,865,255 Patented Dec. 23, 1958 FMEARM WITH TRANSVERSELY MVABLE BARREL CHAMBER Roger Marsh, Hudson, (Ehio, assigner to Weapons, Inc., Hudson, hlo, a corporation of Ghia Application August 3, 1955, Serial No. 526,l72

19 Claims. (Cl. Sli-163) The present invention relates to a firearm wherein the cartridge-receiving chamber at the rear of the barrel and a portion of the breech closure member are mounted for relative longitudinal and transverse movement and more particularly to a rearm wherein the means forming the cartridge-receiving chamber at the breech end of the barrel is mounted for movement to shift said chamber transversely to a loading position in register with a cartridge presented for feeding before said cartridge is fed to said chamber.

According to the present invention the breech closure member or breech bolt and the cartridge-receiving means at the breech end of the barrel are mounted for move ment longitudinally relative to each other and are mounted so that there is relative transverse movement between the cartridgereceiving chamber or barrel chamber and the firing pin carried by the breech closure member. The tiring pin and chamber are moved transversely relative to each other so that the firing pin is out of alinement with the axis of the chamber during feeding of a cartridge into the chamber and until the cartridge is almost all the way in the chamber.

The firearm may, for example, be constructed so that the 'firing pin is out of alinement with the primer of the cartridge in the chamber until the cartridge is within a small fraction of an inch of complet-e chambering. Such a construction reduces the chances of tiring a round before it is chambered and is particularly advantageous in a firearm employing a xed ring pin on the breech bolt. Premature ring, which often occurs in ordinary rearms'employing fixed firing pins when movement of a cartridge into the chamber is abruptly arrested during the feeding stroke, can be avoided by keeping the tiring pin out of allnement with the primer of a cartridge during feeding of the cartridge.

The desired transverse movement between the breech closure member and the cartridge-receiving chamber at the breech end of the barrel may be obtained by mounting all or a portion of the barrel or the breech closure member or the means forming said chamber to rotate,

swing, tilt or otherwise move so as to swing said charnber transversely relative to a portion of the breech closure member. Either the cartridge-receiving chamber or the breech closure member may be mounted for transverse movement, and any suitable mechanism may be provided to obtain the desired sequence of operations. Where the chamber is integral with the barrel, the entire barrel may be mounted to move transversely.

he firearm of the present invention is preferably constructed so that there is relative transverse movement between one chamber at the rear of the barrel and the cartridge to be fed to said chamber, whereby said cartridge is substantially alined with said chamber before being fed thereto. For example, one or more cartridgereceiving chambers may be provided at the breech end of the barrel to swing transversely into alinement with a cartridge presented for feeding. The chamber-forming means and/or the barrel may be rotatably mounted or may be pivotally mounted near the front or rear of the gun to tilt about an axis to a position wherein the chamber is in alinement with the nose of a cartridge presented for feeding. The cartridge-receiving chamber may be located within a barrel block at the breech end of the barrel that is movable transversely relative to the breech closure member independently of or in unison with the barrel. Such barrel block may be separate from the barrel but is preferably fixed to the rear portion of the barrel for movement therewith. Cam means or other suitable means may be associated with the barrel block to shift the cartridge-receiving chamber transversely between a firing position and a loading position.

Moving of the Vcartridge-receiving chamber at the breech end of the barrel substantially into alinement with or in register with the front portion of a cartridge presented for feeding prior to feeding of the cartridge into the barrel provides many advantages. Since the cartridge does not have to move around corners, the chamber can be shaped substantially the same as the outside of'the cartridge case without any taper or cuts at the rear end to facilitate entry of the nose of the cartridge, and the firearm need not have a complicated feed mechanism with special feed ramps. The improved chamber design permits the use of more powerful cartridges with higher pressure loadings.

Since the cartridges move straight into the chamber of the barrel without engaging a ramp and without having to move around corners, it is practicable to employ a cartridge in which the nose is sensitive, such as a cartridge with a high explosive incendiary or other special projectile, or a cartridge wherein the projectile or bullet deforms or comes apart easily, such as an ordinary revolver cartridge having a lead bullet which tends to deform and shave olf in a conventional feed system. It is also practicable to employ shotgun shells, which have no feed noses at the front, and wadcutter or flatnosed-bullet ammunition, which feed very poorly or not at all in conventional arms. The firearm of the present invention may also employ paper shot shells with a multi-projectile charge or other ammunition with non-metallic cartridge cases.

Similarly, this superior feeding system confers advantages if consumable or frangible cartridge cases are used which are comparatively delicate and subject to deformation while passing through the feed mechanisms of conventional firearms. A further advantage of this system, when using such ammunition, is that the chamber and round to be fired are, at the instant of firing, out of register with and separated by a considerable lateral distance from the remaining cartridges in the feeding device, thus minimizing the likelihood of ignition of the reserve ammunition in the event of any leakage of propellant gases in firing.

A very simple feed system may be used in the firearm of the present invention due to the fact that each cartridge is moved straight into the chamber of the barrel. Such a feed system may have very few parts s0 that there is little chance of malfunction due to improper feeding.

Another advantage of the present invention is that it permits an improved bolt design. In an ordinary blowback rearm wherein a cartridge is stripped from a box magazine and moved upwardly and forwardly into the chamber of the barrel, it is necessary to have the top car tridge and thus the magazine lips as high as possible, which makes necessary material removal of metal from the underside of the breach bolt. The present invention permits the use of a stronger and more massive bolt since the magazine may be offset considerably from the centerline of the'barrel in firing position. In a conventional bolt, cutting away of the metal to accommodate the magaseaas's azine or other feed means may make it difcult or even practically impossible to provide a separate movable firing pin since there may notbe enough metal left to accommodate it. Irnrsuch a conventional bolt it may therefore be necessary to provide an integral fixed firing pin. Here, again, the system of the present invention offers distinct advantages if consumable cartridge cases are used, also if cartridges of the type in whichthe propellant carrier is integral with the projectile and is discharged from the muzzle are used, since the type of bolt closure required with such ammunition is generally expected to function as an obturation device (a function normally assigned tothe cartridge case in conventional ammunition) an-d must therefore have a minimum of essentially longitudinal passages or channels such as are found in the configurations of conventional bolts but which maybe virtually eliminated in firearms of the proposed design.

While a firearm with a fixed firing pin has the advantage of` simplicity, it also has` some disadvantages. The slamfiring7 arrangement of letting the bolt jab a protruding -portion of the breech face into the cartridge primer re- `sults not only in an unpleasant firing action due to long delay between trigger pull and firing while the bolt moves forward and due to disturbance of aim by the reciprocating bolt mass but also in lack of dependability under adverse conditions. Dirt in the firearm, weakening of the driving spring, firing with the muzzle elevated, and/or firing of weak orlow-power cartridges may slow down movement of the bolt and its firing pin so as to cause a misfire. In a firearm with a fixed firing pin it often be comes necessary, invorder to assure even partly dependable operation, to increase the stiffness or pressure of the bolt driving spring beyond that required simply to close the action satisfactorily, which sometimes results in failure vof low-power cartridges to operate the firearm. Where the high pressure driving spring is employed as indicated above, malfunctions due to variation in the actuating power or actuating energy of the cartridge may be reduced by employing a booster piston of the type disclosed in my copending application Serial No. 494,754, filed March 16, 1955, or a compensating device of the type disclosed in my copending application Serial No. 461,999, filed October 13, 1954..,

However, the integral fixed firing pin also has disadvantages in a dependable gun. .There is, of course, the dangerof premature firing if the firing pin strikes the primer before the cartridge is chambered sufficiently.

`With a fixed firing pin, a person cannot simply shove the bolt closed by hand when the action balks, since the K cartridge might fire prematurely or'the bolt handle might injure lsaid persons hand upon firing. The improved bolt design of the present invention permits the use of a separate firing pin and retraction of the pin so that the bolt maybe shoved home without firing the cartridge and with no danger of premature firing. Since the firearm of the present invention may have a more massive bolt, it is possible to employ a separate firing pin together with a hammer mechanism or a spring-actuated striker mechanism and to obtain all the advantages of the separatefiring pin. Y

Various means may be employed in the firearm of the present invention to shift the cartridge-receiving chamber of the barrel and the firing pin laterally or transversely relative to each other and/ or to move said chamber transversely into alinement with a cartridge. Such a lateral-ortransverse shiftris usually effected automati-l cally using energy from the propellant lgases in the barrel and is ,preferably effected in response to firing of a cartridge and/or in response to movement of the barrel and vbreech closure member longitudinally relative to each other. The transverse movement maybe obtained by a inyieldablemeans, a positive-acting means, or any other Vsuitable means.v ,'lhe positive-acting means preferably operates in response to relative longitudinal movement between the barrel and the breech closure member and may include cams, levers, bell cranks, links, or the like.

The yieldable means may also include cams, levers yor .the like but usually includes .a spring or other yieldable means which precludes a positive action.

The means employed to obtain the desired lateral movement in the gun of the present invention usually is one of four basic types. In the first type, positive-acting means are employed to move the cartridge-receiving chamber of the barrel transversely to the loading position substantially in alignment with a cartridge before said cartridge enters said chamber and positive-acting means are employed to move the chamber transversely from the loading position to the tiring position. In the second type, transverse movement of the chamber to the loading position is effected by yieldable or spring means and transverse movement to the firing position is effected by positive-acting means (see Figs 24 and 25). The second type has the advantage that the gun is less bulky. In the third type, the chamber is moved transversely to the loading position by positive-acting meansand to the firing position by yieldable or spring means (see Figs 21 to 23 and 35 to 39). In the fourth type the chamber is moved transversely to the loading position by yieldable means and tothe firing position by yieldable means. The firearm of the present invention usually includes one of the above fourV types or a variation thereof.

When. cams are employed as the positive-acting means, the rst and second types are quite satisfactory for any l gun in which the cartridge has sufficient length so that LSU it projects a substantial distance into the chamber before the cams start to move thechamber out of its loading position whereby the cartridge does not tip or jam as the chamber moves laterally. .Howeven operation with such cams in the first and second types is unsatisfactory for extremely short cartridges since it is difiicult to get enough of the cartridge into the chamber before the chamber is moved transversely. The third and fourth types, in which the chamber of the barrel is moved from the loading to the firing position by a spring ory other yieldable means, are useful with very short cartridges since they permit building of a gun in which the bolt pushes the cartridge all the way into the chamber before the barrel veven starts to move out o-f its loading position. Thus, the firearm shown in Figs. 1 to 14, which includes positive acting means of the first type, may be designed for standobtain satisfactory operation in this type of gun with .32 S & N short or .38 S & W short cartridges or other short kcartridges unless special means are provided to push the cartridge all the way into the chamber before the cam moves the barrel, for example as in the guns of Figs. 26 to Si). Figures 2l to 23 and 35 to 39 show the third type of mechanism which would be satisfactory for these sho-rt cartridges.

The operating energy for the firearm of the present invention may he supplied from some -external source, as is the case with manually-operated firearms and with firearms driven by auxiliary motors or the like, but is preferably supplied initially by the propellant which drives ti e projectile or proiectiles, as is the case with self-actuating firearms. Manyvof the advantages of the present invention may be obtained with manually-operated fire arms and firearms driven with auxiliary motors, but the invention is particularly applicable to self-actuating firearms such as semi-automatic rities, machine guns, chine cannons, submachine guns, so-called automatic" pistols` auto-matic rifies, and other automatic or semiautomatic firearms including magazine fed revolvers and the like. As indicated in said copending applications Serial Nos. 461,999 and 494,754, self-actuating firearms are usuallyclassied as blowback firearms, blowforward firearms, locked-breech gas-operated firearms, lockedbreech recoil-operated firearms, gas-operated firearms or a combination of one or more ofthese main types. In a self-actuating firearm, actuating means responsive to the actuating power" or "actuating energy of each round of ammunition (a portion of the energy released by combustion of the propellant) is provided for automatically performing one or more of the actions of the functioning cycle, such as feeding, locking, firing, extracting, cocking, ejecting, or the like.

According to the present invention, the cartridgereceiving chamber at the rear of the barrel is moved laterally or transversely after extraction to a loading position to receive a new cartridge, is held in the loading position until the new cartridge has entered the chamber, and is moved transversely to a tiring position before ring of the new cartridge. It will be apparent that this cycle of operations can be performed on a locked-breech firearm, a gas-operated firearm, o-r various other self-actuating firearms. The cycle of operations of a locked-breech weaponi'of course includes locking and unlocking movements; but any gun, once the breech is unlocked functions during extraction, ejection, feeding and loading as if it were a non-locked weapon. The present invention therefore obviously applies to both locked and unlocked breech firearms.

Where the rearm of the present invention is employed only t0 lire ammunition wherein the cartridge case is designed to be destroyed or consumed in firing or else to be ejected from the muzzle, either separately or with or as the projectile, the cartridge-receiving chamber and a portion of the breech closure member or bolt may be displaced transversely relative to each other toward a loading position almost as soon as the separation of the barrel or chamber from the breech closure or bolt is begun. However, where other ammunition is also to be employed so that an extraction stage is necessary in the cycle of operations to permit removal of the empty cartridge case after ring, an extraction dwell is provided in the cycle during the initial separating movement of the barrel or chamber and the breech closure or bolt, the chamber remaining substantially in its firing position. until extraction of the empty cartridge case is completed.

Where the cartridge case is ejected from the firearmy "1 of the present invention, it may be ejected out the top or side of the firearm or in any other suitable manner, even including downwardly, behind the magazine and in the same plane as the magazine. Conventional means of various types may be employed to extract o-r eject the cartridge case.

The rearm of the present invention may be adapted to handle almost any kind or shape of cartridge and may be designed to operate with a belt feed, a drum or pan feed, a magazine feed, or various other cartridge feeding t means including indexing comparted boxes, feed strips, clips, chargers, solid link belts, stripout link belts, or the like.

According to one embodiment of the present invention the breech bolt is mounted between a pair of parallel cam plates which are mounted for reciprocation on a series of antifriction rollers. The rollers are mounted on transverse frame bolts or rods which extend between parallel side plates of the frame and provide the sole support for the cam plates.

nlIhe breech bolt is provided with a separate firing pin and with a rotatable safety spindle for positioning the: primer-engaging nose o-f the tiring pin in a retracted posi tion behind the cartridge-head recess of the bolt or aniA advanced tiring position in said recess. means may be employed for rotating the safety spindle to position the ring pin in its advanced or retracted position. Such means preferably comprises a rotatable bolt. handle operably connected to the safety spindle. When` the tiring pin is moved to its advanced position by rotating the bolt handle, said pin acts like a co-nventional fixed firing pin.

An object of the present invention is to provide a fire arm with an improved feeding action so as to avoid vlmall? Any suitable n functions and premature tiring during feeding of a car'- tridge to the chamber of the barrel.

A further object of the invention is to provide a rearm that operates satisfactorily with special cartridges which cannot be handled 'oy ordinary firearms.

Another object of the invention is to provide a firearm which permits offsetting of the magazine from the bolt and permits the use of a more massive bolt with a separate firing pin.

A still further object of the invention is to provide a breech bolt with a retractable tiring pin which functions like a fixed tiring pin during tiring of the gun and which may be moved to a safe non-firing position relative to the bolt.

Another object of the invention is to provide a simple firearm which is economical Vto manufacture, easy to assemble and disassemble, and reliable in operation.

A further object of the invention is to provide a firearm with an improved means for mounting the breech bolt.

Another object of the invention is to provide an im proved firearm with novel means for shifting the cartridgereceiving chamber transversely relative to the breech bolt.

Other objects, uses and advantages of the present invention will become apparent from the following description and claims and from the drawings in which:

Figure 1 is a side elevational view with parts broken away and shown in section showing on a reduced scale a blowback firearm constructed according to the present invention;

Figure 2 is a longitudinal vertical sectional view of the breech bolt of Fig. 1 on a larger scale;

Figure 3 is a fragmentary transverse vertical sectional view taken substantially on the line 3-3 of Fig. l and on Aa larger scale;

Figure 4 is a fragmentary longitudinal vertical sectional view taken substantially on the line 4-4 of Fig. 3 and on the same scale;

Figure 5 is a transverse vertical sectional view taken substantially on the line 5 5 of Fig. l and on a larger scale;

Figure 6 is a fragmentary horizontal sectional view taken substantially on the line 6-6 of Fig. l and on a larger scale;

Figure 7 is a top plan View of the firearm of Fig. 1 and on the same scale;

Figure 8 is a longitudinal vertical sectional View with parts omitted and with parts broken away and shown in section illustrating the position of the parts after extraction and at the beginning of ejection;

Figure 9 is a longitudinal vertical sectional view with parts omitted and with parts broken away and shown in section showing the position of the parts when the breech bolt is in its rearmost position;

Figure l0 is a transverse vertical sectional view of the breech bolt taken substantially on the line 10-10 of Fig. 9 and on a larger scale;

Figure 11 is a transverse vertical sectional view taken substantially on the line ll-l of Fig. 1 and on a larger scale;

Figure 12 is a fragmentary transverse vertical sectional view with parts omitted similar to Fig. 11 and on thc same scale showing the lowered position of the sight;

Figure 13 is a fragmentary side elevational view with parts broken away and shown in section taken substantially on the line 13-13 of Fig. 12 and on the same scale;

Figure 14 is a transverse vertical sectional view with parts omitted taken substantially on the line 14--14 of Fig. 1 and on the same scale as Figs. 11 to 13;

Figure l5 is a fragmentary side elevational view on a reduced scale of a modied form ofthe invention with parts omitted and with parts broken away and shown m section;

Figure 16 is a fragmentary transverse vertical sectional view with parts omitted taken substantially on the line iso-16 of Fig. l5 and on a larger scale;

Figure 17 is a fragmentary schematic side elevational View with parts broken away and shown in section showing a modified blowforward firearm constructed according to the present invention', lthe parts being shown in their positions just prior to firing;

Figure 18 is a fragmentary side elevational view similar to Fig. 17 and showing the position of the parts as the barrel moves rearwardly and transversely to index the cartridges;

Figure l is a schematic side elevational view nrt a modilied form of the present invention on a reduced scale, the barrel being shown in its vuppermost position after firing; v v t Figure 2G is a schematic view of the gun of Figure 19 showing the position of the parts just before the b elevated; y

Figure 2lis a schematic side. elevational view on a reduced scale with parts broken away and shown in section showing another modified tirearm according to the present invention, the parts being shown intheir positions at the instant of tiring;

Fivure 21a is a fragmentary vertical sectional view showing a portion of the rearm of Fig. 2l on a larger scale;

Figure 22 is a schematic side elevational view of the firearm of Fig'. 2l showing the position of the parts after ejection and during rearward movement or" the breech bolt;

Figure 23 is a schematic view similar to Figs. 2l and 22 sho-wing the position of the parts during forward movement of the breech bolt and before the bolt engages the base of the cartridge;

Figure 24 is a schematic side elevational View with parts broken away and with parts shown in section showing another modified form of the invention, the parts of the firearm being shown in their positions just prior to tiring;

Figure 25 is a fragmentary side elevational view of the gun of Fig. 24 on a larger scale and with parts broken away and shown in section, the position of the parts when the barrel is in its lowermost position being shown in dotdash lines;

Figure 26 is a fragmentary schematic side elevational View of another modified form of the invention on a reduced scale and with parts omitted and parts broken away, the parts being shown in their positions just prior to firing; Y

Figure 27 is a fragmentary schematic side elevational vieiv of the firearm of Fig. 26 with the side plates omitted:

Figure 28 is a schematic'v'iew similar to 26 and showing the position of the parts inst prior to feeding of a cartridge to the barrel;

Figure 29 is a fragmentary schematic side elevational. view with parts omitted and with parts broken away and shown inl section showing another modified firearm,l the parts being shown in their positions at the instant of firing;

Figure 3f) is a schematic view similar to Fig. 29 showing the position of the parts of the firearm as the breech bolt approaches its rearrnost position;

Figure 3l is a fragmentary side elevational view with parts broken away and shown in section showing another modified form of the present invention;

Figure 32 is a fragmentary transverse vertical sectional view taken substantially on the line 32h-3T3 of Fig. 3l and on the same scale, the position of the bolt handle when the bolt is fully retracted being'shown in dot-dash lines;

Figure 33 Ais a fragmentary horizontal sectional view taken substantially on the line 3.3-33 of Fig. 32 and on the same scale; v

Figure 34 is a fragmentary longitudinal sectional view of the breech bolt taken substantially on the line 34--34 of Fig. 32 and on the same scale;

Figure 35 is a side elevational view with parts omitted and parts broken away and in section showing on Va reduced scale another modified form 'of the invention, the

g parts being shown in their'positions at the instant of flrins;

Figure 36 is a transverse vertical sectional view with parts omitted of the breech bolt taken substantiallyvon the line 36-36 of Fig. 35 and on a larger scale.

Figure 37 is a transverse vertical sectional view of the breech bolt with parts omitted taken substantially on the line 37-37 of Fig. 35 and on the same scale as Fig. 36;

Figure 38 is a fragmentary side elevational View similar to Fig. 35 and on the same scale and showing the position or the partsl as the breech'bolt approachesits rearrnost position; and

Figure 39 is a fragmentary horizontal sectionalvview with parts omitted taken substantially o-n the line indi-` cated at 39-39 in Fig. 35 and on the same scale.

Referring more particularly to the drawings in whichy Vlike parts are identified by the same numerals throughout the several views, Figures l to 14 show a blowbacli til-earm A having a rigid fratrie including a pair of fiat vertical parallel longitudinal side plates 1 and 2 of'thin sheet metal each having a wide intermediate portion 3 of rectangular shape and opposite end porticns 4 and 5 of substantially the same shape. The side plates may be of identical construction and may be symmetrical about their longitudinal and transverse center lines as shown in the rawings. The side plates are held in parallel relation by two vertically alined pairs of parallel frame bolts or connecting bolts 6 and 7 and cylindrical spacing sleeves 8 which fit on the frame bolts and extend between the inside facesV of the side plates. Each o-f the frame bolts is threaded at one'vend to receive a selfflccking hexagonal nut 9 which holds the'side plates against the spacer sleeves as shown in` Figs. 1l and 14. Each of the side plates is provided with a rigid circular reinforcing collar 1i) at its forward end and a rigid longitudinally elongated reinforcing plate 11 along its lower margin. A cover plate 12 is mounted 'across the to-p of theV side plates and has downwardly turned flanges 13 at its opposite sides. Each of said flanges has a pair of ears 14 near the front and rear edges of the intermediate portion 3. The frame bolts 6 and 7 are longitudinally alined and extend through the reinforcing plates 11 and the ears 14 to hold `the frame together. The cover plate 12 is -cut away to provide a central rectangular ejection opening 15 and a pair of downwardly turned vertical flanges 16 at the front and rear margins of said opening. A metal bumper block 17 is welded toor otherwise rigidly connected to the cover plate `l2 and is internally threaded to receive an externally threaded bumper plug 18 having a hexagonal head 19 above the cover plate.

The upper frame bolts 6 and 7 are provided with axially enlarged rectangular heads 2@ and 21. A peep'sight 22 is pivotally mounted on a spfndle 23 rthat extends be-v tween the bolt heads 20 and 21. Longitudinally alined circular ho-les are provided in the heads ,Ztl and 2l to receive opposite ends of the spindle 23 and to permit rotation of the spindle about longitudinal axis. lf desired one end of the spindle may be provided with an axially movable plunger or the like to permit removal of the spindle andthe sight from the frame of the gun without removing the frame bolts. The sight assembly is provided with a lifter lspring 24 whichv biases the sight toward a vertical position as shown in Fig. ll.

The sight is shown herein as being a one-piece metal sheet having lateral flanges ZS-at its opposite ends. Said flanges have longitudinally alined sight apertures 2,6 which define the line ofl sight of the firearm. A sight latch 27 is mounted on the' lower frame bolt 7 vas shown in Figure 13. Said latch isV in the form of a sheet metal spring having a vertical portion with a stud 29 which enters the front sight aperture 2d to hold the sight in its lower position as shown in Fig. l12. A cast aluminum grip 3i) is lmounted between the side plates 1 and 2 at the lower portion of the frame. Thegrip may be mounted on thelfsidefplates in any ysuitable manner, but asherfeiu shown the grip and the side plates are provided with alined circular openings 3f to receive a pair of longitudinally alined horizontal pas 31a. Said pins may be Spirol pins, "Rollpins (supplied by Elastic Stop Nut Corporation of America, Union, N. L), or other commercial spring pin fasteners of the dowel pin type which will tit tightly in the side plates. The grip includes a divided trigger guard 32 at its forward end and an upright hand grip portio-n 33 rearwardly of said trigger guard. The hand grip portion is of generally rectangular cross section and has a magazine opening 34 of substantially rectangular cross section for receiving a conventional box magazine 35.

Any suitable means may be provided for holding the magazine in a predetermined fixed position in the rearm. As herein shown the magazine 35 is provided with a projection or magazine catch 36 and the hand grip portion 33 is Provided with a magazine latch slide 37 which is movable longitudinally into and out of the path of movement of the projection 36. The slide is biased forwardly by a magazine latch spring 38 on the rear face of the hand grip and may be moved longitudinally by a magazine latch trip 39 which is pivotally mounted in the hand grip. The spring 38 is co-nnected to the hand grip by a screw 4) and arranged so that the pressure of the band on the hand grip assists the spring in holding the slide 37 in its forward position.

The magazine 35 may be of the type disclosed in my copending application Serial No. 505,885, led May 4, 1955, or may be of any other suitable type. As herein shown the magazine 35 is a single-row box magazine of rectangular cross section having inturned flanges or lips 41 that extent axially from the rear wall of the magazine substantially to the middle of the magazine and having a platform 42 that is biased toward said lips by a compression spring 43. The spring 43 presses the cartridges in the magazine upwardly toward the lips 41 and holds the uppermost cartridge in a predetermined discharge position at the top of the magazine. The upper front portion of the magazine is cut away in a conventional manner forwardly of the lips 41 so that the upper edge of the front wall of the magazine is below the uppermost cartridge and will not interfere with movement of said cartridge horizontally out of the magazine.

A high strength plastic sleeve 44 of a size to fit on the front portions of the side plates is mounted on said side plates and surrounds the forward portion of the frame as best shown in Figs. 1, 6 and 7. A high ystrength plastic buttstock 45 of a size to lit on the rear portions 4 of the side plates are mounted on said plates and extend from the rear edge of the intermediate portions 3 to the rear of the frame as best shown in Figs. 1 and 7. The buttstock has an integral cheek piece 46 on the left side of the gun which extends forwardly over the heads of the bolts 6 to protect the face of the person firing the gun.

The plastic sleeve 44 and the buttock 45 are readily assembled on the frame by sliding them axially over the side plates.

The trigger guard 32 is shaped to receive a trigger 47 having a central hub 48, a finger piece 49 rearwardly of said hub, and a T-shaped portion 50 extending forwardly from said hub. The hub 48 is mounted on the central portion of the sleeve 8 carried by the lower frame bolt 7 for swinging movements about the axis of said bolt. A pair of spools or rollers 51 are mounted on the sleeve 8 between the sideplates 1 and 2 on opposite sides of the hub 4S as best shown in Fig. 14. Each of the rollers is provided with a circumferential groove 52 of uniform width and depth near one of the side plates. Spools or rollers 53, each having an internally cylindrical surface with a diameter corresponding substantially to the external diameter of the externally cylindrical sleeves 8 are mounted on the sleeve of the uppermost frame bolt 7 and the sleeves of the frame bolts 6 for rotation about the axes of the frame bolts. Each of the rollers 53 extends axially 10 from one side plate to the other and has a pair of circumferential grooves 54 of the same size and shape as the grooves 52. The side faces of the grooves 54 are located in the same longitudinal vertical planes as the side faces of the grooves 52 as shown in Figs. ll and 14.

A pair of flat metal cam plates 55 and 56 of uniform thickness and uniform height are mounted in the grooves 52 and 54 with their side faces substantially in said longitudinal vertical planes. As shown herein the cam plates are rectangular and are of substantially identical construction, each cam plate being provided with a longitudinally elongated cam slot 57 and a trigger notch 58 at its front corner. A breech bolt 59 is mounted between the cam plates and reciprocates longitudinally in unison with said plates. The rollers 51 and 53 provide the sole support for the cam plates and guide said plates longitudinally while preventing transverse or tilting movements of the plates relative to the longitudinal axis of the gun. The side faces of the grooves 52 and 54 hold the cam plates 55 and 56 in parallel relation and parallel to the side plates 1 and 2 during reciprocation of the bolt.

The front portion 50 and of the trigger 47 is biased upwardly by a leaf spring 60 which is connected to the plastic sleeve 44 by a screw 61. When the finger piece 49 is released the spring moves the portion 50 upwardly as shown in Fig. 9 to a position wherein the laterally extending portions 62 of the trigger are in the path of movement of the cam plates 55 and 56. The portions 62 enter the notches 58 of the cam plates as the breech bolt is moved forwardly, but if the finger piece 49 is pulled rearwardly the portion 62 will be lowered out of the path of movement of the cam plates to permit firing of the gun.

The breech bolt 59 is shown herein as being substantially rectangular in transverse cross section and having an integral, centrally located, feed rib 63 of substantially rectangular cross section extending axially along the bottom of the bolt for movement between the magazine lips 4f during reciprocation of the bolt to feed a cartridge from the magazine. A pair of laterally alined studs 64 project from the opposite sides of the bolt and t in laterally alined circular openings in the cam plates 55 and 56 to prevent axial movement of said plates relative to the bolt. An externally cylindrical safety spindle or stop member 65 is mounted for rotation in the bolt 59 about a transverse horizontal axis and extends into alined circular openings in the cam plates 55 and 56 to prevent swinging of the bolt about the axis of the alined studs 64 and to fix the bolt with respect to the cam plates.

A bolt handle 66 is detachably connected to the spindle 65 for movement therewith by means of a screw 67 as best shown in Fig. 3. The bolt handle projects horizontally through a longitudinally elongated horizontal slot 68 in the right side plate 2 which permits movement of the bolt from its foremost to its rearmost position. When the screw 67 and the handle 66 are removed, the bolt and the cam plates may be removed through the rear of the gun. As herein shown, the bolt handle is provided with a pair of lugs 69 which fit in grooves in the safety spindle 65 to prevent rotation of the handle relative to Said spindle.

A circular cartridge-head recess 70 having a fiat vertical cartridge-base-engaging face 71 is provided at the front of the bolt for receiving the head of a cartridge as it is fired. A conventional extractor 72 is mounted on the bolt at the top of the bolt recess 7G to catch the rim of a cartridge as it enters said recess, a cantilever spring 73 being provided t-o bias the front of the extractor toward the center of the recess in the conventional manner. The

bolt is also provided with a laterally offset longitudinal cylindrical bore of a size to receive an externally cylindrical ejector rod 74 near the left side of the feed rib 63 as shown in Figs. 3 and 10.

The bolt also has a cylindrical bore 75 of small diameter and a counterbore 76 with a horizontal longitudinal axis that passes through the center of the bolt recess 70 and i i the axis of the safety spindle 65 as best shown in Figs. 2 and 3. A `separate longitudinal two-position firing pin '77 i's mounted for axial movement in the bore 75 and has an enlarged externally cylindrical piston-like head 7S mounted in the counter-bore 76 between the spindle 65 and the bore 75 and biased toward'said spindle by a helical compression spring '79 surrounding said firing pin.

The safetyrspindle 65 is cut to provide a flat face 89 and a at facel Si substantially perpendicular to the face 3G, the face, 3l being closer to the axis of the spindle. The portion of the spindle 65 adjacent the ejector rod 7d is cut away to` form a slot or groove 82 as shown in Fig. 4 which permits rotation of the spindle from a safe position wherein the face 8l engages ythe headV '78 to a lire position as shown in Fig. 2 wherein the face 372i engages the head 7S. The nose of the tiring pin 77 projects orwardly beyond the bolt face 71 when the spindle is in the fire position'so that thefiring pin will function the same as a xed ring pin. When the spindle is in the safe position, however, said nose is retracted to a position behindthe face 7l so that it cannot strike the primer of a cartridge inthe recess 70.

Since it is dangerous to push the bolt forward by hand when the spin dleis in lire position, it is desirable to provide means on the bolt handle to indicate the position of the firing pin andthe spindle. As herein shown, the bolt handle 66 is provided with a pair of pointed lugs or ears S3 which are pointed in the horizontal direction as shown in Fig. l whenever the safety spindle isin fire position and are pointed vertically whenever the spindle is in the safe position. The sharp projection on the bolt handle will give a warning and discourage anyone from pushing the bolt handle forwardly with the palm of the hand when the ears S3 are pointed horizontally. j

A substantially U-shaped metal back plate or bracket 84. is mounted between the side plates l and 2 at the rear end of the firearm A. The back plate has a hat transverse portion 35' and forwardly extending side portions 86 that are provided with vertically spaced later`- allyfprojecting studs S7 and S8. The studs iit in laterally alined circular openings in the side plates ll and 2 to prevent axial movement of the back plate relative to said plates. The transverse portion 85 is provided with a small circular opening of a size to receive the ejector rod.

The ejector rod is provided with an integral circular collar y89 and is threaded at its rear end to receive a nut 90. A helical butter spring 9i is mounted on the ejector rod between the collar S9 and the transverse portion d5 of the back plate to bias the ejector rod forwardly and to cushion rearward movement of the bolt. As the bolt approaches its rearmost position as shown in Fig. 9, the rear face of the bolt engages the collar S9 to cornpressv the'buffer spring and to move the nut 9d rear-- wardly away from the back plate. i v

Connecting bolts or any other suitable means may be provided to prevent the buttstock 45 from sliding off the rear of the gun. As herein shown, a stock latch 92 is mounted for pivotal movement on a horizontal pivot pin 93 andhas an upwardly projecting catch portion 94 for engaging the front face of the transverse portion S as shown in Fig. l to prevent rearward movement of-the buttstoclt. A spring 95 is provided for holding the catch portion 9d' in a position Yto engage the back plate. The portion of the latchSZ rearwardly of the back plate may be depressed by hand to release the latch Whenever it is desired to remove the buttstock. rthe cam plates 55 and Sopof the breech bolt E9 carried thereby may be biased forwardly in any suitable manner. As herein shown, a recoil spring assembly is mounted on the left side of the rearm A externally of the side plate l and includes a horizontal recoil spring guide rod 96, a helical recoil spring or driving spring 97, and a breech bolt actuating member 93. The front end of the guide'rod 96 is externally threaded to receive a hexagonal i2 mit 99, whichprevents movement of the bolt actuating member forwardly off the end of said rod. A small verticalplate liti@ is welded to the rear end of the guide .rod perpendicular to the axis of said rod to limit reard ward movement of the recoil spring Q7, said plate having a lug itil that projects into a small openingrin the side piate ft to prevent rearward movement of the guide rod relative to said side plate. The bolt actuator g8 has an internally cylindrical surface with a diameter substantiaily equal. to the4 external diameter of the guide rod 96 and' is mounted on said rod to slide longitudinally in unison with the bolt 59, the rear face of said actuator engaging the spring 97 to compress said spring between said face and the front face of the plate 1.63 during rearward movement of the bolt. The bolt actuator has an integral lug MP2 that projects laterally through 'the side plate ll and fits in the front portion of the cam slot 57 of the cam plate as shown in Figs. 7 and 8. A horizontal slot w3, similar to the bolt handle slot 68 of the side plate 2, is provided in the side plate l to receive the lug M2, said slot having sufficient length so that the plate l does not interfere with movement of the lug as the bolt is moved from its foremost to its rearmost position.` An intermediate sheet metal cover iti/l of substantially U-shaped cross section is provided to cover the recoil spring assembly, The opposite end portions of the cover project under the plastic members 4d and d5 and are held thereby in a xed position against the side plate 1 as shown in Fig. 11. The sight 22 is shaped to extend around the cover ILM- as shown in Fig. l2.

A barrel may be mounted on the rearm A in any suitable manner to swing the cartridge-receiving chamber of the barrel transversely relative to the breech bolt. As herein shown, the firearm is provided with a generally cylindrical barrel i495 having a longitudinally extending bore 196 through which travels a bullet fired from a cartridge and having a counterbore or chamber E67' of circular cross section at its breech end coaxial with said bore for receiving the case of a cartridge to be tired. rThe bore 106 is preferably provided with conventional rifling. A barrel block 1138 is rigidly connected to the rear portion of the barrel for movement in unison theren with and is drilled to receive a horizontal cylindrical cam follower or lpin 199 which projects into the cam slot 57.Y Where the slot 57 is provided in both of the plates 55 and 56, the cam pin E09 projects all. the way through the barrel block 08 to engage the marginal surfaces of both slots. As herein shown, the cam pin 199 is rigidly connected to the-barrel block and projects laterally into the cam slot 57 of the cam plate 555 for engagement with the marginal surfaces of said slot to raise and lower the breech end ofthe barrel.

The barrel has an externally cylindrical front portion iii) of reduced diameter and an annular shoulder 111. An annular collar M2 is mountedV on said front portion and against said shoulder. The front portion of the barrel may be pivotally mounted on the frame of the gun A in any suitable manner. a generally cylindrical trunnionblock H3 with an axial length substantially equal to that of the spacingsleeves 8 is pivotally mounted between the front portions 5 of the side plates for swinging movements about a horizontal axis perpendicular to saidjside plates. The trunnion block` is internally threaded to receive a pair of laterally alined trunnion screws M4 which have cylindrical por# tions that extend through alined circular openings in the reinforcing collars it) and the side plates i. and 2 to provide a pivot about which the block swings. The screws 114 have radially enlarged heads which engage the outer face of the collars 10 to hold the side plates against the trunnion block. If desired, set screws 11S may be provided to prevent accidental loosening Vof the trunnion screws. y

`The trunnion .blockl 113 is drilledl midway between its ends landr pt erpendicularA to the pivotalV axis of the As herein shown.

trunnions 114 to provide an internally cylindrical bore with a diameter substantially equal toV that of the barre1 portieri 111i for receiving said barrel portion. The front end of the barrel is externally threaded to receive an internally threaded, tapered, muzzle biast cup or flash hider i o. The trunnion block is assembled on the barrel 1de' by sliding over the front portion 11d until said block engages the collar 112 and the threaded portion of the barrel projects forwardly from the trunnion bloeit. The muzzle cup 116 is then screwed on the barrel until it enga es the trunnion block and forces the collar tightly against the shoulder 111 to hold the barrel in a fixed position relative to the trunnion block.

As herein shown the outer circumferential surface of the cup 116 near the rear end thereof is notched or serrated and a conventional leaf spring or Clicker spring 117 is provided for engaging inthe notches to prevent accidental rotation of said cup or loosening of the connection between the barrel and its trunnion. When the firearm is assembled, the enlarged heads of the screws 114i engage the front surface of the plastic sleeve 44 to prevent the sleeve from sliding forwardly off the side plates.

l't will be noted that the firearm A is of very simple and inexpensive construction and that most of the parts of the firearm may be manufactured employing the simplest molding, machining or forming operations. If desired the side plates 1 and 2 may be identical in co-nstruction, and the cam plates 55 and 56 may also be identical.

Assembly and disassembly of the irearm A is also v-eryieasy. The barrel may readily be removed by loosening the set screws 115, unscrewing the trunnion screws 114, pulling the barrel forwardly, and disengaging the cam pin 163 from the cam slot S7. Once the screws 11d are removed, the plastic sleeve 44 may readily be slid off the front end of the frame. The rear portion of the firearm may also be disassembled readily without removing the frame bolts 6 and 7 by releasing the buttstocit latch 92, sliding the plastic buttstock 45 off the rear end of the frame, springing the side plates off the studs S7 and 5S of the back plate S4, removing the back plate and the ejector rod carried thereby, unscrewing the capscrew 67 to remove the bolt handle 66, and sliding the breach bolt 59 'and the cam plates 55 and 56 rearwardly out of the frame. The cast aluminum grip 3@ may be removed without disassembling the main frame by knocking out the pins 31a, the divided trigger guard 32 permitting removal of the grip without removing the trigger 47. The sight 22 and its spindle 23 may also be removed without disassembling the main frame merely by disconnecting one end of the spindle from the head of the frame bolt.

The cam slot 57 and the cam follower 109 are designed to impart a predetermined transverse swinging movement to the barrel in response to longitudinal movement ofthe breech bolt 59. As herein shown, the cam slot or cam track 57 has front and rear portions 11S and 119, respectively, with a width substantially equal to the diameter of the cam follower 159, and an enlarged intermediate portion 12tl. The upper marginal surfaces of the cam slot 57 comprise front and rear straight surfaces 121 and 122, respectively, parallel to the top and bottom horizontal edges of the cam plate 55 and a smooth inclined surface 123 extendingupwardly from the flat surface 121 to the flat surface 122. The lower marginal surfaces of the slot comprise front and rear straight surfaces 124 and 125, respectively, parallel to and spaced from the surfaces 121 yand 122, and a steeply inclined surface 126 extending upwardly from the fiat surface 124 to the surface 125. The surface 126 must be inclined rather steeply, so as to raise the rear end of the be rel from its lowermost position to its upperon while the cam plate 55 moves longitudinalpress the driving spring.

ly a distance substantially less than the length of a cartridge case to be fed to the barrel chamber ltl.

Figure l shows the position of the parts when the barrel chamber 167 is in firing position and the bolt is at its foremost position. At the instant of firing the bore 1% and the chamber iii are axially alined with the boit recess 7d and the front of the bolt is substantially in engagement with the rear face of the breech block 10?. At this time the cam follower 109 is located in the front portion 119 of the cam slot. When the breech bolt approaches its rearmost position as shown in Fig. 9 the cam follower 199 is in the front portion 11S of the cam slot and the barrel chamber 107 is in its lowermost loading or feeding position substantially in alinement with the uppermost cartridge in the magazine 35. As herein shown, the chamber 107 is of a size to receive standrd'S VSpecial orV :357 Magnum rimmed cartridges and the bore 106 is yof a size to receive the bullets from such cartridges. The magazine 35 is provided with one row of rimmed cartridges 127 having bullets 12S of a size to lit the bore 106 and a cartridge case 129 of a size to tit in the chamber 167. The cartridge case has an externally cylindrical body portion 130 and a radially extending rim 131 with a diameter slightly greater than the internal diameter of the bore 106.

The case has a flat base with a conventional centrally located primer which is engaged by the tiring pin 77 when the head of the cartridge enters the bolt recess 7G. The magazine lips 41 hold the uppermost cartridge 127 in the magazine 35 in a predetermined discharge position substantially coaxial with the chamber 107 when said chamber is in its loading position as shown in Fig. 9.

If the trigger fingerpiece is released as the breech bolt moves forwardly from its rearmost position, the laterally extending portions 62 of the trigger will engage the trigger notch 5S and halt movement of the breech bolt before it reaches the uppermost cartridge in the magazine. As the ngerpiece is pulled rearwardly the portions 62 will slide downwardly across the front lower edges of the lcam plates to release the bolt. The driving spring will then force the bolt forwardly until the feed rib 63 engages the base of the uppermost Cartridge in the magazine between the magazine lips d1 to feed the cartridge into the chamber 107. During feeding of the cartridge into the chamber the cam follower 109 remains in engagement with the surface 124 until the cartridge case 129 is a substantial distance in the chamber and the rim 131 is clear of the magazine lips 41.

Upon further forward movement of the bolt, the cam follower 169 engages the surface 126 to raise the chamber 107 and the cartridge 127 therein from the position of Fig. 9 to the firing position of Fig. l. Before the rim 131 of the cartridge in the chamber 1tl'7 enters the bolt recess 7, the cam follower 109 engages the cam surface to position the bolt 59 and the chamber 107 coaxial with the firing pin. In the last twentieth of an inch or so of forward movement of the bolt the movement of the cartridge stops, and the rim 131 engages the rear face of the barrel and begins to enter the bolt recess 70.

At the instant of firing as shown in Fig. l the cartridge is fully chambered, the rim 131 is in the bolt recess 70 and the extractor engages the front face of the rim to grip the cartridge case. The pressure produced by the propellant gases in the barrel after firing of the cartridge forces the bullet 12S through the bore and at the same time forces the breech bolt rearwardly to com- During the first portion of the rearward movement of the bolt, the extractor pulls the empty cartridge case out of the barrel, said case holding follower 109 substantially in engagement with the cam surface 122. After the front end of the cartridge case is a substantial distance rearwardly of the barrel the cam follower 109 engages the inclined cam surface 123 to initiate lowering of the chamber 107. During such lowering the front end of the ejector rod 74 engages the 1.1i base of the cartridge case as shown lin Fig. 8 to eject the case upwardly through the opening 15. As rearward movement continues the cam follower engages the top surface 121 of the cam portion 118 to position the chamber 11B-7 in its lowermost position coaxial with the uppermost cartridge 127 of the magazine.

The energy from the propellant gases after firing is suicient to move the breech bolt against the collar S9 and to compress the buffer spring 91. Each time the bolt moves rearwardly past the magazine 35, a new cartridge is advanced upwardly by the spring d3 to a discharge position against Athe magazine lips The energy stored by the driving spring 97 during rearward movement of the bolt is then expended to push the bolt forwardly against the base of the new cartridge and to feed the cartridge into the firing chamber 1177. A substantial portion'of the cartridge case 1290i the cartridge fed to the firing chamber enters the chamber` before the inclined surface 126 engages the cam follower 199 to move the chamber out of its lowermost loading position so that the cartridge will not catch on themagazine lips 411 and will not tip or jam during elevation of the barrel whereby the new cartridge is lifted by the barrel to a position wherein its primer is axially alined with the firing pin 77 before said firing pin strikes said primer.V As the chamber 1197 arrives at its uppermost firing position, the flat top surface of the barrel block 10d engages the flat bottom surface of the bumper plug 13. 1t will be noted that the cam follower 1119 does not enter the rear portion 119 of the cam slot until the cartridge in the chamber 1517 is within a small fraction of an inch of complete chambering so that the firing pin 77 is out of alinement with the primer of the cartridge until said cartridge is almost completely chambered whereby the danger of prematurefiring is reduced.

It will be noted that the flat horizontal top and bottom surfaces of the cam plates 55 and 56 remain in engagement with the rollers 51 and 53 at the bottoms of the eight circumferential grooves 52 and 5ft as the breech bolt S9 moves from its foremost position adjacent the barrel to its rearmost position adjacent the buffer spring. The cam plates are supported and held parallel to the side plates 1 and 2 solely by the rollers 51 and 5'3 and may be easily removed after removal of the barrel, the back plate 84, and the recoil spring assembly merely by pulling the bolt rearwardly from between the side plates. The roller suspension system employed on the firearm A is simple and has many advantages over conventional systems whether or not the barr-el is mounted to move transversely relative to the bolt.

It will be understood that such a roller suspension system` including the novel method of mounting the bolt on parallel side plates may be employed in a simple blowback firearm and various other firearms wherein the barrel is held against lateral movement. Figures and 16 show a modified blowback rearm A that is substantially identical to the firearm A except ythat the barrel is not mounted for transverse swinging move* ments. 'Ehe firearm A may be constructed exactly the same as the firearm A described above except that the bumper block 17 and bumper plug 18 are omitted, the upper front roller 53 is replaced, the box magazineis of slightly different construction, the barrel is of different construction, the barrel is mounted in a different manner, and the cam slot 57 is omitted or does not function. The barrel of the firearm A is provided with a trunnion block 113 and trunnion screw 114 like the firearm A and is pivotaliy mounted on the side plates 1 and 2, but the rear end of the barrel is held against lateral movement oy a barrel stirrupv132 mounted on the spacing sleeve 8 of the upper frame bolt d. A pair of rollers 51 are mounted on said spacing sleeve on opposite .sides of thezstirrupas shown in Fig. l6 to guide the cam plates .5S Aand Sd. Like the hub portion d of the trigger,

`the upper portion of the stirrup has an internally cylin- 15 drical opening of a size to fit the externally cylindrical sleeve 8 and a width to fit between the rollers 51.

As herein shown, the firearm A has a barrel lflSa with any externally cylindrical intermediate portion 133 that ts tightly in an 'internally cylindrical opening 134 in the stirrup. Rearwardly of the stirrup the barrel has a radially enlarged portion 13S with an external diameter greater than the diameter of the opening 134 and a conventional feed lamp 136 for guiding the nose of a cartridge into the chamber of the barrel. The bore and the chamber of the barrel 105a are the same as those of the barrel 1S and the front portion of the barrel 105er may be substantially the same as that of the barrel 105. However, as herein shown the barrel 111551 has a front end portion 137 of reduced diameter and of a size to slide through the trunnion block 113 that is externally threaded throughout its length to receive an internally threaded collar 138 at the rear of the trunnion block and the cup 116 at the front of the trunnion block. Said collar and said cup engage opposite faces of the trunnion block to prevent movement of the barrel relative to said block. Like the collar 112, the collar 138 has a fixed position spaced forwardly from the foremost position of the cam plates SS andl S6 so as not to engage'said plates as they reciprocate. The barrel 105e may be removed without disturbing the frame bolts 6 and 7 by removing the buttstock 45, the bolt handle 66, and the back plate 34, removing the trunnion screws 114- and the plastic sleeve 44, unscrewing the blast cup 116, removing the trunnion block 113 from the end portion 137 of the barrel, unscrewing the collar 133, and sliding the barrel rearwardly through the opening 134 of the stirrup while removing the breech bolt 59 and the cam plates and 56 rearwardly through the opening at the back of the frame.

The feed ramp 136 of the barrel is necessary since the uppermost cartridge in the magazine is below the axis of the barrel bore. As herein shown, a single-row box magazine 35cz'is provided which is identical to the magazine 35 except that the magazine lips 41a are inclined slightly with respect to the horizontal, said lips tilting the noses of the cartridges 127 upwardly for better feeding. As the breech bolt moves forwardly after the finger piece 4% of the trigger 47 is pulled, the feed rib 63-of the bolt passes between the magazine lips 41a and engages the base of a cartridge in the magazine to feed the cartridge forwardly. As forward movement of the bolt continues, the nose o-f the bullet 128 rides up the ramp 136 into the barrel chamber. As soon as the rim 131 of the cartridge in the chamber is alined with the bolt recess and forward movement of the cartridge is arrested, the head of the cartridge enters said recess and the firing pin 77 strikes the primer of the cartridge to yignite the propellant in the cartridge.

As herein shown, the firearm A is designed to operate with rimmed cartridges 127, but it will be apparent that such a firearm may readily be designed to operate with rimless cartridges which are more apt to be used in blowforward guns of this general type. However, the firearm A' cannot be designed to handle as many different types of ammunitionas the firearm A due to the tortuous path which must be traveled by each round fed to the barrel. Sensitive-nosecartridges, for example, would be unsuitable for use with the feed ramp 136.

The present invention applies to firearms wherein the breech -closure member is stationary as well as to firearms employing movable breech bolts. Figures 17 and 18 show a blowforward rearm 'A2 which automatically indexes a feed strip to advance cartridges throughl the rearm. The firearm includes a fixed breech closure member or breechblock 139, a pair of side plates 140 rigidly connected to the breechbloclr and extending, forwardly therefrom, and a barrel 1111 pivotally mounted between the side plates for transverse swinging movements and longitudinal sliding movements relative to the side plates. The barrel has a conventional longitudinal rifled bore 142 and an internally cylindrical cartridge-receiving chamber 143 coaxial with the bore and shaped to receive a rimmed cartridge 144 having a cartridge case 145 with a radially projecting circular rim 146. The barrel has an externally cylindrical forward portion 147 and an externally threaded front end portion 148. An internally threaded muzzle brake 149 may be mounted on said end portion, if desired, to assist in moving the barrel forwardlly. The muzzle brake has radial openings 150 and a front circular opening 151 coaxial with the bore 142 and having a diameter corresponding substantially to that of said bore.

A generally annular trunnion block 152 similar to the block 113 has trunnions journaled in the side plates 140 for swinging movements about an axis perpendicular to the side plates and has an internally cylindrical opening perpendicular to the trunnions of a size for slidably receiving the cylindrical barrel portion 147. The trunnion block 152 also has a lateral recess for receiving the front end 153 of a recoil spring guide rod 154. The rear portion of said guide rod is slidably mounted in an internally cylindrical opening in a barrel block 155 which holds the guide rod parallel to the barrel while permitting longitudinal sliding of the barrel relative to said rod. An annular collar 156 is rigidly connected to the rod near the trunnion block, and a helical driving spring or recoil spring 157 is mounted on the rod 154 to be compressed between said collar and the barrel block 155 as the barrel moves forwardly. The barrel block is rigidly mounted on the barrel for movement in unison therewith and is provided with a cam pin or follower 158 which projects laterally into cam slots or cam tracks 159 in the side plates 140.

The pin and slot 158 and 159 of the firearm A2 function like the pin 109 and slot 57 of the firearm A to move the barrel chamber transversely in response to relative longitudinal movement between the barrel and the breech closure member. However, a cam island 160 is provided at the center of each cam slot 159 to hold the barrel in its firing position during extraction and to hold the barrel in its loading position during the return stroke of the barrel toward the breechblock. The cam slot 159 has an outer marginal surface shaped like that of the slot 57 and has front and rear inclined marginal surfaces 161 and 162, respectively, similar to the surfaces 123 and 126, which engage the cam pin 158 to move the rear end of the barrel transversely as the barrel slides longitudinally.

As herein shown, a series of cartridges 144 are mounted in regularly spaced parallel relation in a metal feed strip or feed plate 163 of uniform thickness having a series of equally spaced alined openings therein of suitable shape for receiving and supporting the cartridge cases 145, said openings having a diameter less than that of the rims 146 so that said cases are held against forward movement out of the feed strip. The feed strip is placed between the barrel and the breechblock so as to provide a continuous supply of cartridges and is free to move transversely relative to the breechblock between the side plates 140.

A fixed liring pin or any other suitable firing pin may be mounted in the breechblock 139 to lire the gun. However, in a blowforward firearm it is usually preferable to employ a separate hammer-actuated firing pin or a spring-actuated striker which moves forwardly from the breechblock to strike the primer of the cartridge. As

herein shown, a separate longitudinal firing pin 164 is mounted for axial sliding movements in the breechblock 139 and is actuated automatically in a conventional manner to strike the primer of a cartridge 144 in the barrel chamber 143 when said chamber is in tiring po Fsition coaxial with the ring pin as shown in Fig. 17.

At the instant of firing the cam pin 158 is at the rear of the cam track 159, the rim 146 of the cartridge case a of the cartridge in the cham'r er 143 engages the at front surface of the breechblock 139, and the front and rear faces of the feed strip 163 engage the front of said rim and the flat rear face of the barrel 141 whereby the cartridge is completely chambered. On firing the pressure of the propellant gases forces the bullet from the case a through the rifling of the barrel bore 142 and through the muzzle brake 149 to cause forward movement of the barrel and compression of the recoil spring 157. A pair of stationary laterally alined feed strip ledges or stops 165 and 166 are mounted on the side plates 140 to limit forward longitudinal movement of the feed strip 163 and the cartridges carried thereby with the barrel so that the case a is extracted from the chamber 143 as the barrel moves forwardly. The cam island engages the pin 158 to hold the barrel chamber in its uppermost firing position until the barrel is clear of the case a. After the cartridge case is fully extracted the pin 153 strikes the inclined surface 161 of the cam track to move the rear end of the barrel laterally towards a loading position. As the recoil spring is further compressed the pin 158 approaches the forward end of the cam track and the barrel chamber 143 is moved to a loading position substantially in longitudinal alinement with the case b of the next cartridge 144 in the feed strip. The recoil spring 157 then causes rearward movement of the barrel toward the breechblock 139, the cam island 160 engaging the pin 158 to hold the rear end of the barrel in its lowermost loading position as the barrel moves rearwardly so that the mouth of the chamber registers with the cartridge case b and envelope the mouth of said case as the cartridge enters the barrel. The cam island 160'holds the chamber 143 in its loading position until a substantial portion of the cartridge case b enters said chamber.

The feed strip 163 does not move transversely as the barrel moves forwardly and rearwardly from the empty cartridge case a to the cartridge case b of the next cartridge, but as the cartridge enters the barrel chamber 143, said feed strip permits slight tilting of the cartridge as it enters the barrel to accommodate barrel angle changes during the stroke of the barrel.

After the case b has entered the barrel the cam pin 158 engages the inclined cam surface 162 as shown in Fig. 18 to move the barrel transversely towards its tiring position. The transverse movement of the barrel chamber 143 causes transverse movement of the cartridge cases a and b and the feed strip 163 and automatically indexes the feed strip. As soon as the cam pin 158 reaches the rear of the cam track 159 to return the barrel chamber to its firing position coaxial with the tiring pin 164, said firing pin Strikes the primer of the cartridge 144 in said chamber to start another cycle of operations. The blow-forward firearm will fire automatically and will automatically advance the feed strip 163 to supply cartridges to the barrel.

If desired a spring finger 167 may be employed to catch the rim of a cartridge to prevent downward movement of the feed strip while barrel is away from cartridges. Where a fixed firing pin is employed, the spring finger 167 may be employed to hold the feed strip against the feed ledges and 166 so that the cartridges clear the tiring pin as the barrel is moved laterally.

While the firearms of Figs. l to 14, 17 and 18 employ cams to move the barrel chamber transversely, it will be apparent that other positive-acting means may also be employed. Figures 19 and 20 show in diagrammatic form a simple blowback firearm A3 constructed according to the present invention and including a rigid frame 16S, a barrel 169 pivotally mounted at its front end on said frame for transverse swinging movement, a breech bolt 170 mounted for longitudinal sliding movement relative to said frame, a driving spring or bolt return spring 171 carried by the frame for yieldably resisting rearward movement of the bolt, a conventional single-row box magazine 172 for supplying cartridges to be fed to the barrel, and a cam lever 173 mounted for swinging movement on a horizontal pivot pin 174 carried by .the frame.

After tiring the breech bolt 17@ moves rearwardly to extract and eject the empty cartridge case. After the extraction is completed the upper rear portion of the bolt strikes the rear of the lever 173 to swing said lever clockwise whereby the front portion of the lever engages the top of the barrel to lower the barrel chamber to a loading position in longitudinal alinement with the upper- I most cartridge in the magazine 172. During forward movement of the bolt a feed rib 175 on the bottom of the bolt passes between the magazine lips and engages the base of the uppermost cartridge in the magazine to feed the cartridge into the chamber of the barrel 169.

After the cartridge has entered the chamber a substantial distance and is clear of the magazine lips, cam horns 176 projecting forwardly from the bolt engage lugs 177 projecting laterally from the barrel to initiate movement of the barrel chamber from the loading to the tiring position. Thelugs ride up inclined surfaces of the cam horns as shown in Fig. 2O to return the barrel chamber and the bore to a firing position coaxial with the firing pin of the bolt before said pin strikes the primer o-f the cartridge in said chamber.

In the firearms of the present invention, means is provided for causing relative transverse movement between the cartridge-receiving chamber and the ring pin or other portion of the breech closure member. ln the firearms described above the cartridge-receiving chamber or firing chamber at the rear of the barrel is formed in the barrel and has a Vfixed position relative to the barrel bore, but it will be apparent that such chamber may be formed in a separate member which rotates, slides or swings transversely relative to the barrel bore, in which case the bore need not move transversely relative to the breech closure member or breech bolt.

Figures 2l, 21a, 22 and 23 show in diagrammatic' form a modied blowback firearm A4 wherein the cartridgereceiving chamber or firing chamber is separate from the barrel and is movable transversely relative thereto. The self-actuating firearm A4 has a rigid metal frame 178 which is internally threaded at its front end to receive an externally threaded rear end portion 179 of a rigid longitudinal barrel 105b which Vis held in a xed position relative to the frame. The barrel has a longitudinal bore 186i) that may be provided with conventional rifling. A separate barrel block or slide 10815 is mounted at the rear of the barrel 185b and is shaped to provide a cartridgereceiving chamber or tiring chamber 107i) that may be moved transversely into axial alinement with the barrel bore 106b.

A breech bolt 180 is mounted on the frame 178 rearwardly of the barrel block 108!) for longitudinal sliding movement on the frame toward and away from said barrel block, a driving spring or bolt return spring 181 yieldably resisting movement of the bolt rearwardly away from the barrel. A conventional single-row box magazine 182 is carried by the frame at the rear of the barrel block for supplying cartridges to be fed to the barrel chamber 1tl7b. A lever 183 is pivotally mounted at its rear end on a pivot pin 184 carried by a rear portion of the frame and is slotted, at its fro-nt end to fit on a pin 185 carried by the lower end of the barrel block so that the front end of said lever moves vupwardlyand downwardly with the cartridge-receiving chamber 107b. The barrel block is mounted for vertical sliding move ments between pairs of parallel guides 186 mounted on the frame 178 at opposite sides of the rearm and is biased upwardly by a lifter spring 187 on the frame which yieldably resists movement of the cartridge-receiving chamber downwardly out of register with the barrel bore.

A slight longitudinal movement of the barrel block may be permitted by the guides 186 if a booster eifectis desired, but it is usually preferable to prevent any longitudinal movement of said block relative to the frame 178.

If desired, a bumper block or stop 18b may be rigidly mounted. on the'frame 178 to limit upward movement of thebiarrelblock .1tl8b by the spring 187, said bumper yblock .engaging the top ofthe barrel block when the chamber 1Mb yreaches its uppermost firing position in laxial alinement with the bore lttltib as shown in Figs. 2l

and 2 2.: The portion of the barrel block 108b projecting forwardly of the vertical guides 186 is externally cylindrical and is movable into engagement with a similarly "shaped surface on the botto-m of an arcuate protuberance ythe at vertical faces of the barrel and the barrel block after tiring, it is preferable to provide sealing means for reducing such leakage. As herein shown, the barrel block is provided with a cylindrical counterbore at its forward `end which receives an externally cylindrical packing bushing 381 of substantially uniform radial thickness which sealingly engages the cylindrical surface'of the counterbore. -During firing, the gas pressure acts on the back face of the bushing 381 and slides the bushing forwardly against the flat rear face of the barrel 105b to seal the space between said rear face and the front face of the barrel block, the flat front face of the bushing sealingly engaging said rear face as best shown in Fig. 21a. The rear faceV of the barrel is ush with the at vertical face of the frame 178 below the protuberance 188 so that the bushing 381 is free to slide vertically over said flat face as shown in Fig. 23.

- Mean-s is provided for swinging the lever 183 iri response to longitudinal movementrof the breech. bolt vso as to move the cartridge-receiving chamber 1071) from its ring position in register with the barrel bore to a pre-determined loading position in register with the uppermost rcartridge in the magazine 182. Such means includes a cam dog 189 of substantially segmental form that ispivotally mounted on the central portion of the lever 183 and a leaf spring 198 mounted on the lever for biasing the cam dog upwardly in the clockwise direction -as indicated in Figs. 2l to 23.

Fig. 2l shows the positions of the parts of the firearm A4 at the instant of firing. At this time thebarrel block 10817 is supported by the spring 187 in its uppermost ring position with the cartridge-receiving chamber 107k coaxial with the barrel and with the fixed tiring pin on the bolt, the cam dog being rearwardly of the bolt and in its uppermost position. After extraction and ejection, the bolt 180 rides rearwardly over the cam dog and the chamber 10717 remains in its uppermost ring position as shown in Fig. 22. As the bolt passes the cam dog, said dog returns from a depressed position as shown in Fig. 22 to an interception position. As the bolt is pushed forwardly by the spring 181,`the bolt engages the cam 4dog to depress the dog and the lever 183, to compress the spring 187, and to lower the chamber 10719 to a lowermost loadingposition -as shown in Fig. 23 wherein the chamber issubstantially in register with the uppermost cartridge ofthe magazine. Y

While the cartridge-receiving chamber 17b is in its loading position, a central feed lip191 on the bottom of the bolt passes between the upper lips of the magazine 182 and engages the base of the uppermost cartridge in said magazine to feed the cartridge into said chamber. After the .cartridge isr moved a substantial distance into said chamber and outof Contact with the magazine, the breech bolt rides oif the cam dog and thelifter-spring 187 returns 'said chamber toits uppermost fir-ing position.

21 Thereafter the cartridge in said chamber is fired and the cycle is repeated. This arrangement is particularly advantageous since the gun may be designed so that the cartridge is almost fully chambered before the cartridgereceiving chamber is moved upwardly from its lowermost loading position.

If desired, yieldable means may be provided for depressing the barrel. Figures 24 and 25 show a modified form of the present invention wherein the barrel is moved transversely by a spring in response to rearward movement of the bolt. As shown in these figures, a blowback firearm A is provided having a rigid frame 192 with a receiver 193, a barrel 194 having trunnions 195 journaled in the front portion of the frame, a breech bolt 196 mounted in the receiver 193 for longitudinal sliding movements toward and away from the barrel, a recoil spring or driving spring 197 interposed between the bolt and the'rear wall of the'r'eceiver for Vbiasing the bolt toward the barrel, and a conventional box magazine 198 mounted in a fixed position in the receiver for supplying cartridges to be fed to the barrel. The barrel 194 has a conventional bore and a conventional firing chamber or counterbore 199 for receiving cartridges from the magazines. The bolt 196 has a circular bolt recess 200, a fixed firing pin at the center of said recess, and a feed rib 201 that passes between the magazine lips to advance a cartridge into the barrel.

A longitudinally elongated slot 202 is provided in the top wall of the receiver 193 to receive a vertical bolt handle 203 that projects upwardly from the bolt. Rigidly connected to the bolt handle is a lcnigtudinally extending guide rod 204 having an enlarged portion 205 at its forward end. A crank 206 is mounted for swinging movements on a pivot pin 207 rigidly connected to the frame 192 and projects through an opening 208 in the top wall of the frame. The crank has an upright springengaging portion 209 adjacent the rod 204 and a fiat barrel-engaging portion 210 substantially perpendicular to said upright portion. A helical compression spring 211 is mounted on the guide rod 204 between the crank portion 209 and the rod head 205 and engages said crank portion to resist movement of said crank portion toward said head and to hold the crank portion 210 against the barrel. A barrel block or lug 212 is rigdly mounted on the rear end of the barrel and engages the flat under surface of the crank portion 210. A .pair of integral cam horns 213 are provided on opposite sides of the breech bolt 196 and project forwardly therefrom for engaging the bottom of the barrel block on opposite sides of the barrel, each of said horns having an inclined barrel-engaging surface 214.

The operation of the firearm A5 is much like that of the other blowback firearms described above. At the instant of firing the flat front face of the breech holt 196 is substantially in engagement with the at rear face of the barrel 1 94, the cam horns 213 engage the bottom of the barrel block 212 to support the chamber 199 in its uppermost tiring position coaxial with the bolt recess 200, the rim of the cartridge is in the bolt recess and is gripped by the extracto-r, and the crank 206 is pressed by the spring 211 against the top of the barrel block to hol-d the barrel block against the cam horns 214 as shown in Figs. 24 and 25. Just after firing the pressure of the propellant gases cause the bolt 196 to move rearward y to extract the empty cartridge case from the chamber, said case supporting the rear end of the barrel until the mouth of the case clears the end of the barrel. After extraction is completed the empty cartridge case is ejected in the conventional manner and rearward movement of the bolt continues so as to further compress the reccil spring 197 and the barrel-actuating spring 211.

As the bolt moves rearwardly the pressure of the spring 211 on the upright crank portion 209 increases so that the crank 206 is rotated to depress the barrel 194 to a lower loading position as shown in dot-dash lines in Fig. 25 substantially in alinement with the uppermost cartridge in the magazine 198. After the rear end of the barrel is lowered by the yieldable connection between the bolt and the barrel, the bolt is shoved forwazdly by the recoil spring 197 and the feed rib 201 pushes the uppermost -cartridge longitudinally out cf the magazine into the barrel. After the cartridge is clear of the magazine and part way into the chamber 199, the incl ned surface 214 engages the bottom o-f the barrel block to lift the barrel chamber from its loading position to its firing position in alinement with the firing pin. After the cartridge reaches the firing position the xed firing pin carried by the bolt strikes the primer of the cartridge to tire the gun.

The firearm A5 will function satisfactorily with the elements described above. However, in order to reduce the danger of jamming when the barrel is not properly "depressed, it'is often preferable to Vprovide means for arresting forward movement of the belt whenever the barrel is above its loading posiion. As herein shown, an interlock mechanism is provided including interengaging levers 215 and 216, said levers being pivotally mounted on a pair of lateral horizontal pins carried by the frame 192. The barrel 194 has a downwardly projecting per tion 217 that engages the front end of the lever 216 and the bolt 196 has a downwardly projecting portion 218 rearward of the magazine 198 that engages the front end of the lever. The rear end of the lever 216 engages the front end of the lever 215 so that movement of (ne lever about its pivotal axis swings the other lever in the opposite direction about its pivotal axis.

The normal position of the levers is shown in solid lines in Figs. 24 and 25. When the barrel is properly depressed to its loading position, the portion 217 engages the lever 216 and lowers the rear end of the lever 215 out of the path of travel of the bolt as shown in dotdash lines in Fig. 25. However, if the barrel is not properly depressed and does no-t engage the lever 216 before forward movement of the bolt begins, the front end of the lever 215 projects into the path of movement of the bolt and engages the front face of the portion 218 to halt movement of the bolt before the front of the bolt reaches the magazine. This prevents feeding of a cartridge toward the barrel until the barrel is properly depressed to receive the cartridge.

It will be noted that the cam slo-t 57 of the firearm A has a widened portion so that the barrel remains in its lower loading position until the cartridge is fed to the barrel chamber. Figures 26 to 30 show modified forms of the present invention wherein the cam sl:t is of substantially uniform width throughout its length and means are provided for feeding the cartridge from the magazine to the barrel before the bolt reaches the magaz1ne.

Figures 26 and 27 show in diagrammatic form a blowback firearm A6 which may be constructed substantially like the firearm A. The rearm Ai has a rigid frame including a pair of parallel fiat side plates 219 and a back plate 220 rigidly connected to said side plates. A breech bolt 221 is rigidy connected to a pair of flat parallel cam plates 222 and 223 of identical construction which are mounted on the frame for movement longitudinally between the side plates parall.l to said side plates. The bolt has a conventional extractor 224 on its right side, a conventional bolt recess 225 with a conventional fixed firing pin or the like at the center of the recess, and an internally cylindrical opening near its left side for receiving an ejector rod 226 that extends forwardly from the back plate 221. A recoil spring or bolt return spring 227 is mounted on the ejector rod between the back plate and the bolt to press the bolt forwardly.

The firearm A6 has a barrel 228 similar to the barrel of the firearm A an'l having laterally alined horizontal trunnions 229 journaled in the side plates 219. A barrel block 230 is ridigidly mounted on the rear end of the barrel and has an internally cylindrical opening of a size to receive a horizontal cam pin or lfollower 231 that outvits length corresponding substantially to the diameter of the cam pin 231. The opposite 'end portions of the cam pin fit in the slots 232 `and slide relative to said slots as the bolt reciprocates. Each slot 232 has straight horizontal front, and rear portions233 and 234 and an inclined intermediate portion 235 that extends upwardly from the front portion tothe rear portion. A horizontal ejection port 236 is' provided in the right cam plate 223 just below the rear portion 234 of the Vcam slot,'sad port being large enough to permit ejection of cartridge cases laterally through the side of the gun. Where it is desired to make bothcam plates the same, a similar port may also be provided inthe left cam plate.

A conventional single-row box magazine 237 is supported in a fixed position on the frame to store a row of cartridges 238 for firing in the chamber 239 of the barrel. The magazine 237 and the cam plates 222 and 223 may be mounted in any suitable manner, for example like the magazine 35 and the cam plates 55 and 56 of the firearm A.

An externally cylindrical stud 240 projects horizontally from each side of the bolt 221 into a circular opening in the cam plate to connect the bolt to the side plates, and

van externally cylindrical spindle or pin 241 extends -through the bolt into circular openings in the cam plates for the same purpose. A bolt handle similar to the handle 66 may be mounted on the spindle 241 if desired,

and where a two-position firing pin is provided in the bolt, said spindle and bolt handle may be substantially the same as the spindle 65 and handle 66 of the firearm A.

The operation of the blowback firearm A6 during rearward movement of the bolt is substantially the same as vthat of the firearm A. At the instant of firing the front of the bolt is substantially in engagement-with the rear face of the barrel, the cam pin 231 is near the rear ends of the cam slots 232, the chamber 239 and the bore of the barrel are coaxial with the bolt recess 225 and the ring pin, and the upper cartridge 238 in the magazine is held below the upper `magazine lips by a horizontal .rammer or feed bar 242 that is rigidly connected to the bottom of the bolt and projects a substantial distance forwardly therefrom. The barrel has a front lower portion 243 that is cut away on an incline to clear the rammer.

The cam pin 231 remains in the straight portions 234 A of the cam slots 232 until the empty cartridge case is fully removed from the chamber by the extractor 224 and is clear of the barrel. Thereafter the inclined marginal walls of the inclined portions 235 engage the pin to lower the barrel chamber 239 to a predetermined .loading position. During rearward movement of the bolt the front face 244 of the ejector rod 226 engages the base of the empty cartridge case in the bolt recess 225 to eject the case horizontally out the side ejection ,port 236 and the rammer 242 rides off the uppermost cartridge to permit the cartridge to move upwardly to a predetermined discharge position against the magazine lips. The cam pin 231 is then in its lowermost position .in the front portions 233 of the cam slots and the charnber 239 is in its loading position substantially in alinement with the uppermost cartridge 238 in the magazine. Rearward movement of the bolt ycontinues until the cam pin is near the front of the cam slots.

The compressed spring 227 then forces the bolt for wardly and the rammer 242 engages the base of the .portions233 of the cam slots. After `the cartridge is clear ofthe magazine and is supported by the barrel,

Amay slidably engagev the rammer as the barrel is elevated.

It will bev understood that the rammer employed to feed the cartridge into the barrel before the barrel is moved out of its lowermost loading position may be movable independentlyof the bolt or in response to movement of the barrel or the bolt. Figures 29 and 30 show in schematic forma modified blowback firearm A7 which is constructed substantially the same as the firearm A6 except that separate means are provided for moving the rammer forwardly inl response to rearward movement of the bolt. The firearm A'7 has a bolt 22111 and abarrel 228a substantiallythe same as the bolt 221 and the barrel 228 and mountedon the side plates 219 in the vsame way. The barrel 228:1 is substantiallyY the same as the barrel 228 except that they lower front portion 243a thereof is not cut away. The bolt 221a is substantially the same as the bolt 221, but the extractor A22411 is located above the bolt` recess 225 and the ejector is located below the firing pin to eject the cartridge upwardly as inthe lfirearm A.. However, it will be apparent that side ejection may also be employed asin the firearm A6 in which ca se the ejector and extractorfcould be mounted asin the bolt 221.

- The bolt group`including the cam plates 222 and 223 and the bolt 22la-is mounted for longitudinal-reciprocation parallel topthe'side plates 219 asin the firearm A6 =and is biased forwardly by a suitable recoil spring or driving'spring, for example as in the firearm A. T'ne -cam pin 231 of the barrelblock cooperates with theycam slot 232 to raise and lower the rear er1-dA of the barrel 228a as in the firearm A6. i f

Means is provided for feeding cartridges 238 from the magazine 237 vto the chamber 239 of the barrel 228a .while the cam pin 231 is in the straight lower front portion'of the cam slot 232 including a rammer or feed bar 242a .of a size to fit between the upper lips of `the Amagazine 237,.,a rammer crank 246 and a crank return .bar 247. The rammer crank has a hub 248 journaled on a horizontal pivot pin 249 and upper and lower arms '250'and 251, respectively; integrally connected to said hub and adapted to engage said crank return bar and said rammer, respectively. The rammer has an ejector nose 252 at its forward end and va'slot 253 for receiving the lower arm 251. A lateral stud 254 is rigidly mounted on the rear of the cam plate 222 for engaging thefront of the crank arm 250 to swing the crank counterclockwise and thereturn bar 247 has front and rear laterally extending end portions 255 and 256 for engaging Ythe `rear of the stud 254 and the rear face 'of the arm 250,

respectively.

The operation of the firearm A7 is much like that of the firearm A6. At the instant of firing the ejector nose 252 is in a slot 245 in the bottom of the bolt 221a rearwardly of the magazine 237, the front face of the bolt 221a is substantially in engagement with the rear face-of the barrel 22811, the barrel chamber 239 is coaxial with the bolt recess 225 and the firing pin, the cam pin 231 is adjacent the front end of the cam slot 232, and the rim of the cartridge 233 in said barrel chamber is in said bolt recess and is gripped by the extractor 224a as shown in Fig. 29. rhe cam pin 231 remains inthe upper straight portion 233 -of thecam slot until the empty cartridge case is extracted from the barrel chamber, and as rearward movement of the bolt continuesthe fiat front vertical face of the ejector nose 252 engages the base of the cartridge case to ejectthe case vertically outthe top of the:l gun andthe inclined surface of the lcam slot portion 235 engages the cam pin 231 to ndepress the rear 25 end of the barrel. The stud 254 moves rearwardly with the bolt and engages the upper crank arm 250 to move said crankA arm rearwardly and to move the lower crank arm 251 forwardly. The forwardly moving arm 251 engages the front wall of the slot 253 to push the rammer 242a forwardly during rearward movement of the bolt. The front face of the remmer 242e engages the base of the uppermost cartridge in the magazine 237 after the cam pin 231 reaches its lowermost position in the lower portion 233 of the cam slot and after the barrel chamber 239 has been moved to its lowermost loading position substantially in longitudinal alinement with said uppermost cartridge. As rearward movement of the breech bolt continues the ramnier feeds the cartridge into the `barrel chamber as shown in Fig. 30 until the cartridge is fully chambered. The forward feeding of the cartridge Vis therefore completed before the recoil spring moves the Vbolt forwardly.

As the bolt moves forwardly the inclined portion of the cam slot 232 engages the cam pin 231 to return the rear portion of the barrel to its uppermost firing position .and the stud 254 engages the front end portion 255 of the rammer crank return bar 247 to move said bar forwardly with the bolt. As the return bar moves forwardly its rear end po-rtion 256 engages the rear face of the upper crank arm 250 to return said crank arm and the rammer .to the position shown in Fig. 29 before thefiring pin strikes the primer of the cartridge in the barrel chamber.

It will be apparent that the lateral or transverse movement between the barrel and the breech bolt or breech closure member necessary to effect transverse movement of firing pinand barrel chamber relative to each other may be obtained by moving a portion of the breech closure member transversely relative to the frame as well as by moving the barrel transversely. Figures 3l to 34 show a modified blowback firearm A8 wherein positive acting cam means are employed to rotate the breech bolt in response to longitudinal sliding movement of the breech bolt relative to the frame. The firearm A8 comprises a rigid frame including a generally annular receiver 258 having an internally cylindrical bore 259 in which is slidably mounted an externally cylindrical breech bolt 260. The bolt is provided with an internally threaded radial hole to receive an externally threaded portion of a combined bolt handle and cam follower 261 which is rigidly mounted on the right side of the bolt and projects radially through a cam slot 262 in the receiver 258. A feed slot or magazine opening 263 is provided in the bottom of the receiver and a side ejectionl opening 264 is provided in the receiver between the feed slot and the cam slot. A conventional single-row box magazine 265 containing a row of conventional rimless cartridges 266 is mounted in a fixed position relative to the receiver with its inturned feed lips projecting into the feed slot 263, the uppermost cartridge in the magazine being held by said lips in a predetermined discharge position in said slot below the outer cylindrical surface of the breech bolt. A small integral feed rib 267 is provided on the bottom of the bolt that projects radially beyond said cylindrical surface into the feed slot 263.

The breech bolt is provided with a substantially circular cartridge-head recess 268 near the bottom of the front bolt surface of a size to receive the head of a cartridge 266, a conventional spring-pressed extractor 269 mounted at the right side of said recess to enter the extractor groove of the cartridge and to grip said head, and a conventional fixed firing pin 270 at the center of the cartridge-head recess for striking the primer of the cartridge. The breech bolt has a longitudinal bore and counterbore of a size to receive a spring-loaded horizontal ejector rod 271 having a radially enlarged head 272 at its rear end, the axis of said rod being on the left side of the firing pin. The front cartridge-engaging face of the ejector rod projects into the recess 268 behind the foremost surfaces of the bolt when said rod is in its 26 foremost position relative to the bolt. spring plate 273 is pressed against the flat rear face of the bolt and against the head 272 by a bolt return spring or driving spring 274. The receiver is internally threaded to receive an externally threaded back plate or plug 275 -bolt is at its foremost position substantially in engagement with the flat front wall of the receiver 258, the bolt handle 261 is at the front of the cam slot 262, the firing pin 276i and the cartridge-head recess 268 are in their lowermost position coaxial with the barrel chamber 279 and directly above the magazine 26S, and the feed rib 267 is at the left side of the slot 263 clear of the magazine as shown in Figs. 31 to 33.

The cam slot 262 has straight top and bottom marginal surfaces 28@ and 281 and inclined front and rear marginal surfaces 282 and 283 which engage the bolt handle 261 during longitudinal movement of the breech bolt, said surfaces preferably being `radially disposed as indicated in Fig. 32. After firing and during extraction of the empty cartridge case from the barrel chamber, the bolt handle or cam follower 261 engages the straight surface 281 of the cam slot and the cartridge-head recess 268 remains in its firing position coaxial with the barrel chamber. After the extraction is completed and the empty cartridge case is clear of the barrel, the bolt handle arrives at the inclined surface 233 to initiate rotation of the bolt and the spring 274 increases the pressure of the plate 273 on the extractor rod head 272 to move the front surface of said rod forwardly beyond the bottom of the cartridge-head recess 268 whereby the empty cartridge case is ejected laterally through the opening 264. As the bolt handle rides up the inclined surface 283, the recess 268 is swung laterally out of register with the barrel chamber 279 and the feed rib 267 is swung laterally toward the magazine. When the bolt reaches its rearmost position in full recoil, the bolt handle 261 is adjacent the rear of the cam slot 262 in its uppermost position as shown in dot-dash lines in Fig. 32, the feed rib 267 is spaced rearwardly from the base of the uppermost cartridge in the magazine and is longitudinally alined with the primer of said cartridge and with the barrel chamber, and the cartridge-head recess 268 is out of longitudinal alinement with said cartridge and said barrel. As the breech bolt is advanced by the recoil spring 274, the fiat front face of the feed rib 267 moves into engagement with the uppermost cartridge 266 in the magazine and said feed rib moves straight ahead between the magazine lips to feed the cartridge into the chamber 279. During this forward movement the bolt handle rides along the straight cam surface 280 so that no lateral movement is imparted to the feed rib at this time. After the feed rib has moved a substantial distance between the magazine lips and after the nose of the cartridge rides up the feed ramp 277, the bolt handle rides down the inclined cam surface 282 to return the bolt recess 268 to its original position coaxial with the barrel chamber. However, said recess is not brought into alinement with the base of the cartridge until the cartridge is almost completely chambered so that there is little danger of premature firing due to engagement of the tiring pin with the base of the cartridge before the cartridge is chanibered.

The front portion of the ejector rod 271 projects into the cartridge-head recess 268 during feeding of the cartridge into the barrel chamber but does not extend beyond the front face of the bolt so as to interfere with movement of the cartridge into the barrel. After the A flat circular-

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