US3177601A - Bolt stop for use with tandem-type magazines - Google Patents

Description

R. MEUNIER April 13, 1965 5 Sheets-Sheet 2 Filed Dec.

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BOLT STOP FOR USE WITH TANDEM-TYPE MAGAZINES Filed Dec. 18, 1963 I 3 Sheets-Sheet 5 INVENTOR. Ember Mannie 1:

United States Patent Orifice Patented Apr. 13, 1965 3,177,6dl BQLT STiU-P FGR USE WlTl-l TANDEM-TYPE MAGAZINES Robert Meunier, New Bedford, Mass assignor to the United States of America as represented by the Secretary of the Army Filed Dec: 18, 1963, Ser. No. 331,633 3 Claims. (Cl. 42-18) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to firearms which are fed with cartridges from a magazine and are provided with a reciprocal bolt and it pertains more particularly to devices for stopping a bolt in the recoil position when the last cartridge in the magazine is fired.

There has recently been developed for firearm use a tandem-type magazine which consists of a forward compartment and a rear compartment each adapted for holding a stack of cartridges. The cartridges are fed first from the front compartment into the barrel chamber by a rammer on the front end of a reciprocating bolt. When the forward compartment is emptied, the cartridges are successively transferred by a feed pawl on the rear end of the bolt from the rear to the front compartment and then, during the neXt cycle, the cartridge is transferred by the ramrner from the front compartment into the barrel chamber.

It has been discovered that the conventional type of bolt stop, which is immediately effective when the last round is displaced from the magazine, is not suitable for use with such a feeding system because, when the rear compartment of the magazine is emptied so that the follower therein will normally actuate the bolt stop into effective position, a round remains in the front compartment.

It is, therefore, the object of this invention to provide a bolt stop which will be delayed one cycle after the last cartridge is removed from the magazine rear compartment before being effective so that the last round in the magazine is fired before the bolt is stopped.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is a longitudinally cross-sectioned side view of the rear section of a firearm showing the bolt in battery position, a cartridge in the front chamber of the tandem magazine and the last cartridge in the rear compartment in the feeding position respective thereto;

FIG. 2 is an enlarged fragmentary view similar to FIG. 1 but showing the last round transferred from the rear to the front compartment and the actuator displaced to the intermediate position;

FIG. 3 is a view similar to FIG. 2 but showing the actuator pivotally displaced by the bolt and transfer of the cartridge from the front chamber to the barrel chamber initiated;

FIG. 4 is a view similar to FIG. 3 but showing the bolt stopped in recoil position by the bolt stop following discharge of the last cartridge; and

PEG. 5 is an exploded, perspective view of the bolt stop and actuator assembly.

Shown in the figures is a firearm 12 having a receiver 14 and a barrel 15 with a chamber 16. Provided in receiver 14 is a magazine well 15' for receiving a tandemtype magazine having a front compartment 22 and a rear compartment 24 each of which is adapted to receive a stack of cartridges 26. Cartridges 26 in front compartment 22 are biased upwardly by a follower 23 to a feeding position therein while the cartridges in rear compartment 24 are biased upwardly to the feeding position therein by a spring-biased follower 29. Means (not shown), such as are disclosed in application Serial No. 286,874 filed June 10, 1963, now Patent No. 3,140,- 554 for a Double, Tandem-Arranged Magazine Feeding Device by Richard H. Colby, hold the cartridges 26 in rear compartment 24 depressed from the feeding position therein until front compartment 22 is emptied.

A bolt 39 is slidingly mounted in receiver 14 for reciprocation between a recoil position and a battery position responsive to discharge of a cartridge 26 in chamber 16 and is spring-biased to battery position. A rammer 32 on front end of bolt 30 is arranged to transfer the feeding position cartridge 26 in front compartment 22 into chamber 16 and a spring-biased feed pawl 34- pivotally mounted on the rear end of the bolt is arranged to successively transfer the cartridges from rear compartment 24 from the depressed position, after being released to the front compartment, responsive to reciprocation of the bolt.

Provided in receiver lid rearwardly of magazine well 13 is a vertical bore 36 which is located so as to inter rupt the rear wall of the magazine well to form a vertical port 33. A well 49 extends upwardly in receiver 14 parallel to bore 36 and diametrically opposite magazine well is so as to interrupt such bore and form an orifice 42. Well 49 is terminated at the upper end by a terminal surface 44 Bore 36 and well 46 slidingly receive a bolt stop 46 which includes a cylindrical body 48 received by such bore and a semicylindrical tag 5i) which extends from the bottom end of the body so as to be received by such well. A spring 52 is disposed between terminal surface 44 and tab 59 for biasing bolt stop 45 downwardly to a retracted position.

integrally formed on top of body 48 is a head portion 54 which is essentially rectangular in configuration and which includes an arm 56 that projects forwardly through port 38 so as to be contacted by follower 29, when the last cartridge 26 in rear compartment 24 is transferred to front compartment 22, to displace bolt stop 46 to an elevated position against the bias of spring 52. When bolt stop ddis in the elevated position, a stopping surface 53 on the rear end of head portion 54 is positioned for contact by feed pawl 44 to stop forward displacement of bolt 30 from the recoil position.

In order to delay the stopping of bolt 30 one cycle so that the last cartridge 26 is transferred from front compartment 22 into barrel 16 and fired, there is pivotally mounted on head portion 56 an actuator dii which interrupts full displacement of the bolt stop to the elevated position one firing cycle as hereinafter described.

Actuator 60 includes two similar side plates 62; which are integrally joined at the upper portions thereof by a transverse cross-piece 64 so that the actuator straddles head portion 54 with the side plates positioned along the sides thereof. A pin es extends transversely through side plates 62 and head portion 54 to mount actuator 60 for pivotal displacement thereon. When actuator 60 is vertically disposed, cross-piece 64 projects above head portion 54 so as to be contactable by feed pawl 34 during forward displacement of bolt 30 from recoil position. The front edges of the side plates 62 are positioned forwardly of the front face of head portion 54 and extending rearwardly into the forwardly extending portion of each of the side plates, from the front end thereof, is a recess 68 which accommodates a shaft 7t) that extends transversely through receiver 14. Each of the recesses 68 is terminated at the top end by a planar surface '72 and at the bottom end by a flat 7d. Surfaces 72 and flats 74 are spaced a distance equal to approximately one-half the distance required for displacement of bolt stop 46 from the retracted position wherein stopping surface 78 is clear of contact by feed pawl 34 to the extended position. A lip 76 extends upwardly from each of the flats 74 at the forward end thereof to form a cavity 73 which partially receives shaft 70 when the shaft is in contact with such flat. A spring 80 is operationally disposed between head portion 54 and actuator 60 for rotating the actuator in a counterclockwise direction (as shown in the figures) to where the underside of crosspiece 64 contacts an angular surface 82 which extends downwardly and forwardly from the top of the head portion. When cross'piece 64 is in contact With surface 82, actuator 69 is vertically disposed and shaft 70 is received by cavities 78.

Operation Actuator 69 is normally biased to the vertical position by spring 80 and bolt stop 46 is biased by spring 52 to the retracted position where surface 72 of the actuator contacts shaft 76} (FIG. 1). When the last cartridge 26 in rear compartment 24 is transferred therefrom to front compartment 22 (FIG. 2), follower 29 in the rear compartment contacts arm 56 to elevate the bolt stop against the bias of spring 52. The upper displacement of bolt stop 76 is limited by contact of flats 74 with shaft 70 so that the bolt stop is stopped at an intermediate position between the retracted and extended positions. In this intermediate position, cross-piece 6 is positioned so as to be contacted by feed pawl 34 but so that stopping surface 58 is clear thereof. Thus, during the next reciprocal cycle of bolt 30 (FIG. 3), wherein the last car tridge 36 in magazine 20 is transferred from front compartment 22 into chamber 16 and fired, feed pawl 34 contacts cross-piece 64 during displacement of the bolt from the recoil position causing actuator 60 to rotate free of shaft 78, whereby bolt stop 46 is free to be dis placed upwardly by spring 52 to the extended position. The upward displacement of bolt stop 46 is stopped in the extended position by contact with the top side of arm 56 with shaft 70. Actuator 60 is held against rotation by spring 80 back to its normal position by contact of lip 76 with shaft 70. Thus, during the reciprocation of bolt 30 responsive to discharge of the last cartridge 26 (FIG. 4), the bolt is stopped adjacent recoil position by contact of feed pawl 34 with stopping surface 58.

Firearm 12 is rearmed by removing the emptied magazine 20 and installing a full one. During this replacement of magazine 20, bolt 30 remains engaged by bolt stop 46 which is held in the extended position by the frictional contact of feed pawl 34 with stopping surface 58. When the full magazine 20 is installed, firearm 12 is charged by actuation of the firearm charging device (not shown) which pulls back on bolt 30 whereby the frictional contact between bolt stop 46 and feed pawl 34 is relieved, whereby the bolt stop is displaced to the retracted position by spring 52 and bolt 30 is freed for forward displacement to battery position transferring top cartridge 26 in front compartment 22 into chamber 16 for discharge during such forward displacement. When bolt stop 46 is displaced to the retracted position, actuator 60 is free to be rotated by spring 80 back to its 4 vertical position with shaft 76 being received by recess 68.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1. In a firearm, a receiver, a barrel with a cartridge chamber, a magazine, a front compartment in said magazine for receiving a stack of cartridges, a first springbiased follower disposed in said front compartment for biasing said stack of cartridges therein to a feeding position respective to said front compartment, a rear compartment in said magazine for receiving a stack of cartridges, a second spring-biased follower disposed in said rear compartment for biasing said stack of cartridges therein to a feeding position respective to said rear compartment, a bolt disposed in said receiver for cyclic reciprocation between a recoil and a battery position, a rammer disposed on said bolt for successively transferring the cartridges from said front compartment into the cartridge chamber, a feed pawl mounted on said bolt for successively transferring the cartridges from said rear compartment to said front compartment when the stack of cartridges therein is depleted, a bolt stop displaceable by said second follower to a position for stopping said bolt adjacent the recoil position when the last one of the cartridges in said rear compartment is transferred to said front compartment, a shaft through said receiver, and an actuator on said bolt stop arranged for operational cooperation with said feed pawl and said shaft to delay full displacement of said bolt stop .to the position for stopping said bolt one reciprocal cycle after the last one of the cartridges in said rear compartment is transferred to said front compartment.

2. The combination as defined in claim 1 and including a head portion on said bolt stop, means for pivotally mounting said actuator on said head portion, a recess in said actuator for receiving said shaft surface, a flat formed by said recess and arranged to be contacted by said shaft to stop the displacement of said bolt stop before reaching the position for stopping said bolt, and a crosspiece on said actuator arranged so as to be contactable by said feed pawl, when said flat is in contact with said shaft, so that said actuator is pivotally displaceable by said feed pawl to free said fiat from said shaft and permit continued displacement of said bolt stop to the position for stopping said bolt.

3. The combination as defined in claim 2 and including an arm on said bolt stop disposed for contact by said second follower to transfer displacement thereof to said bolt stop for displacement thereof to the position for stopping said bolt and for contact by said shaft to stop displacement of said bolt stop at the position of stopping said bolt, and a spring operationally disposed between said head portion and said actuator for biasing said actuator to a position wherein said fiat is contactable by said shaft.

No references cited.

BENJAMIN A. BORCHELT, Primary Examiner.

Claims (1)

1. IN A FIREARM, A RECEIVER, A BARREL WITH A CARTRIDGE CHAMBER, A MAGAZINE, A FRONT COMPARTMENT IN SAID MAGAZINE FOR RECEIVING A STACK OF CARTRIDGES, A FIRST SPRINGBIASED FOLLOWER DISPOSED IN SAID FRONT COMPARTMENT FOR BIASING SAID STACK OF CARTRIDGES THEREIN TO A FEEDING POSITION RESPECTIVE TO SAID FRONT COMPARTMENT, A REAR COMPARTMENT IN SAID MAGAZINE FOR RECEIVING A STACK OF CARTRIDGES, A SECOND SPRING-BIASED FOLLOWER DISPOSED IN SAID REAR COMPARTMENT FOR BIASING SAID STACK OF CARTRIDGES THEREIN TO A FEEDING POSITION RESPECTIVE TO SAID REAR COMPARTMENT, A BOLT DISPOSED IN SAID RECEIVER FOR CYCLIC RECIPROCATION BETWEEN A RECOIL AND A BATTERY POSITION, A RAMMER DISPOSED ON SAID BOLT FOR SUCCESSIVELY TRANSFERRING THE CARTRIDGES FROM SAID FRONT COMPARTMENT INTO THE CARTRIDGE CHAMBER, A FEED PAWL MOUNTED ON SAID BOLT FOR SUCCESSIVELY TRANSFERRING THE CARTRIDGES FROM SAID REAR COMPARTMENT TO SAID FRONT COMPARTMENT WHEN THE STACK OF CARTRIDGES THEREIN IS DEPLETED, A BOLT STOP DISPLACEABLE BY SAID SECOND FOLLOWER TO A POSITION FOR STOPPING SAID BOLT ADJACENT THE RECOIL POSITION WHEN THE LAST ONE OF THE CARTRIDGES IN SAID REAR COMPARTMENT IS TRANSFERRED TO SAID FRONT COMPARTMENT, A SHAFT THROUGH SAID

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