US3489060A - Automatic delayed blowback carbine - Google Patents

Description

Jan. 1 1970 M. P. MAROCCHI 3,489,060

AUTOMATIC DELAYED BLOWBACK CARBTNE Filed Feb. 26, 1968 ll 1 33A magi, 3 I Y United States Patent Oil Free 3,489,060 Patented Jan. 13, 1970 3,489,060 AUTOMATIC DELAYED BLOWBACK CARBINE Michele Pietro Marocchi, Via V. Alfieri 2/ A, Gardone Val T rompia, Brescia, Italy Filed Feb. 26, 1968, Ser. No. 708,077 Claims priority, application Italy, Apr. 22, 1967, 2 748/67 Int. Cl. F41c /02 US. Cl. 89-139 1 Claim ABSTRACT OF THE DISCLOSURE The present invention relates to automatic blowback carbines and, particularly, to an automatic blowback carbine in which, besides a unique hammer-control member, there is provided a guideless breech block or bolt of predetermined and appropirate mass and actuated by a suitably calibrated spring, on which breech block or bolt there is mounted a conventional firing pin acting either on the central region or on the annular region of a Floberttype cartridge or shell.

In accordance with the invention, another object of the present carbine resides in the recoiling action of the breech block or bolt following the percussion of the shell. The recoiling action is retarded with respect to the percussion action by the expansion of the shell case due to the pressure from the gas generated bythe explosion. This retarding action prevents the expulsion of the shell case from the barrel of the carbin until the gas pressure, which is decreasing as the bullet moves down the barrel, ceases to hold the shell case in its expanded condition, so that, as a result, the shell case recoils under the residual existing gas pressure and forces the breech block or bolt to move backward to cock the hammer and permit the ejection of the spent shell case and the placing of a new shell in the barrel.

A further object of the device of the invention resides in the method of assembly of the barrel of the carbine to its adjacent stock portion or receiver. The assembly may be readily effected by means of a threaded element, such as a lock screw, which can be unthreaded simply by employing the edge of a conventional coin so as to separate the barrel of the carbine.

Still a further object of the invention is to provide for the rapid separation of the trigger housing or trigger guard from the carbine, the trigger housing or trigger guard being secured to the carbine receiver by a lock pin which may be removed from its seat by means of a spherically pointed object such as a ball pen, thus eliminating the need for special tools.

These and other objects of the present invention will become apparent from the following detailed description of the embodiments thereof and from the accompanying drawings, in which:

FIGURE 1 shows in cross-section the assembled components of the carbine of the invention;

FIGURE 2 shows in cross-section the trigger housing or trigger guard separated from the receiver;

FIGURE 3 is a partial cross-section of the receiver and of the breech block or bolt obtained in the direction of arrows AA of FIGURE 1;

FIGURE 4 shows in cross-section a detail of the extractor of the spent shell case; and

FIGURE 5 shows an enlarged section of the device obtained in the direction of arrows BB of FIGURE 1.

Referring now to the drawings, the carbine of the invention comprises a receiver 1 on which is mounted, by means of a lock pin 30, the trigger housing 2 for the hammer 6. Hammer 6 carries the trigger 3 and is actuated by a spring 7 suitably guided by a stem or rod 8. Also mounted on the receiver 1 are the trip lever 4 and pawl 5 which, hinged at 31, permits the intermittent operation (shooting) of the carbine.

The carbine, furthermore, comprises the breech block or bolt 9 of suitably predetermined mass (size and weight), actuated by the spring 11 and seated within a circular and guideless seat 10. Longitudinal movements of the breech block or bolt are, thus, possible. Inside the breech block or bolt 9 there is provided a longitudinal seat within which is located the firing pin 13, actuated by a spring 14 and acting upon either the central region or the annular region of the shell 15, when this is positioned within the barrel 16 of the carbine.

On the front or forward portion of the underguard of the trigger housing 2, there is hinged by means of pin 17 a sear 18 which, actuated by a spring 19, includes a lateral tooth or pawl 20 acting on the outer surface of the magazine 21. The magazine 21 is seated Within a vertical seat suitably provided in the receiver of the carbine.

Also in the front or forward portion of the trigger housing 2, there is secured a plate 22 which terminates on its upper extremity in a finger 23, which is to be seated in the longitudinal seat 24 suitably provided on the breech block or bolt 9. This finger 23 serves the purpose of actually ejecting the spent shell case. Finally, the barrel 16 of the carbine is secured to the front end portion of the receiver 1 by means of a lock screw 25, as shown in FIGURE 1 of the drawings.

As stated hereabove, the shells to be employed in the carbine of the present invention are of the Flobert type and comprise the shell case with the appropriate charge and the bullet. By pressing the trigger 3, the hammer 6 is disengaged and the firing pin 13 strikes the shell. Due to the particular elastic properties of the material forming the shell case and due to the high pressure of the explosion gases, there is an expansion of the shell case proper, which expansion is such as to cause the shell case to remain lodged in the barrel of the carbine while the bullet travels along the barrel.

The lodging of the shell case in the barrel is assured, not only by the expansion of the shell case but also by the mass of the breech block or bolt 9, by the action of the spring 11 and by the action of the spring 7 of hammer 6. The shell case remains in the barrel until, due to the movement of the bullet and the consequent increase in volume of the explosion gases, the gas pressure decreases to a point where the shell case, no longer expanded, recoils and forces the breech block or bolt 9 to move rapidly backward to reload automatically the hammer 6 while a new cartridge or shell is introduced by the action of the spring of the magazine in the barrel and while the spent shell case is ejected by the finger 23 of the plate 22 from the carbine.

Therefore, the opening of the breech block or bolt 9 is substantially retarded with respect to the explosion of the shell, so as to exploit fully the gas pressure for shooting and for impressing upon the bullet a greater velocity.

It is to be observed that the extractor 32 of the shell 3 case is fixed, that is, not hinged, and is an integral part of the breech block or bolt 9, as it can be seen from FIGURE 4 of the drawings.

Finally, it is also to be noted that the lock pin 30 of the trigger housing 2 is provided with an annular discharge seat 33, in which is located a sphere or ball 34 or any other suitable means having a rounded terminal actuated by a spring, which (as shown in FIGURE 5) is the same spring 19 which acts upon the sear 18 of the magazine 21.

What is claimed is:

1. In an automatic blow-back carbine of the type using an elastic, expandable shell case, the combination comprising: a barrel, a receiver secured to said barrel, said receiver having a seat, a recoila'ble' breech block of predetermined mass slidably mounted in said seat of said receiver, said breech block having a longitudinal seat, a calibrated spring for axially displacing said breech block, an assembly comprising a trigger housing and a hammer, said assembly being removably secured to said receiver and detachable therefrom as a unit, said trigger housing comprising a plate having, in the front portion thereof, an upwardly displaced finger-like extremity for expelling the spent shell case from the carbine, said finger-like extremity being disposed within said longitudinal seat in said breech block, said assembly being secured to said receiver by a transverse lock pin having an annular seat, said lock pin being held in position by a spring actuated, spherically-terminated element acting upon said annular seat in said lock pin, and a spring biased firing pin slidably positioned in said breech block in axial alignment with a portion of the shell whereby, after the maximum force of the explosion gas is exploded the recoil of said breech block is momentarily retarded by the expansion of the shell case within said barrel to prevent expulsion of the shell case until the gas pressure is reduced and ceases to hold the shell case at which time said breech block recoils under residual, existing gas pressure to cock said hammer and to place a new shell in said barrel.

References Cited UNITED STATES PATENTS 2,655,839 10/ 3 Ruger a 42-25 X 2,926,445 3/ 196 0 Green et al 422 5 3,079,718 3/1963 Allyn 89194 X 3,253,362 5/1966 Gitchell 4225 X 836,554 11/1906 Bennett 89-194 1,083,384 1/1914 Browning 89-194 X 1,165,621 12/1915 Nelson 89-180 2,457,001 12/1948 Smith 4269 X BENJAMIN A. BORCHELT, Primary Examiner STEPHEN C. BENTLEY, Assistant Examiner US. Cl. X.R.

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