Patent GB-1055236-A (GB)
Title: Improvements in semi-automatic or automatic guns
IPC: F41A9/32
Filed: 1964-08-31
Abstract: 1,055,236. Machine guns. BREVETS AERO-MECANIQUES S.A. Aug. 31, 1964 [Sept. 19, 1963], No. 35485/64. Heading F3C. In a semi-automatic or automatic gun having a breech body 34 reciprocating in a cylindrical breech casing 1 of circular cross-section provided with upper and lower openings 2, 3 for the feed and discharge of cartridges, the breech body is supported on two slideways 70, 71, at least one of which has in the semi-cylindrical space limited by a plane through the openings 2, 3 two guiding surfaces 74 constituted by the edges of two projections 72 starting from the inner wall of the casing 1, the arrangement being such that there is left between the projections 72, the casing 1 and the volume swept by the breech body, an elongated space in which is housed a mechanism of the gun. A first mechanism is housed between the projections 72 of the lefthand slideway and consists of a tubular cam 75 journalled at its ends in bearings 76, 77 and provided with a helical slot 83 in which is engaged a finger 84 of the breech body 34 so that as the latter reciprocates the cam 75 oscillates about its longitudinal axis. A toothed portion 89 of cam 75 co-operates with a toothed sector 90 having a recess 91 in which is engaged a roller 87 carried by a cartridge-feed lever 85. The movement of the cam 75 is thus transmitted to the lever 85 which reciprocates transversely to feed a belt and the cartridges which are guided by surface 28a into the breech. A second mechanism housed between the projections 72 of the right-hand slideway is for stopping firing and comprises sear 94 and its shockabsorbing device formed by spring 95 and its tubular guide 96. Sear 94 and guide 96 are mounted on a pin 97 which extends through slots in the right-hand guideway. Sear 94 has a stop face 94a which co-operates with a stop face 99 provided on the breech body. A spring-mounted piston 100 urges the sear 94 towards the breech body and the front edge 102 of recess 101 is capable of fully ensuring the engagement of sear 94 with the stop face 99 of breech body 34 during compression of spring 95. A third mechanism is housed below the left-hand slideway and consists of a return spring 105 disposed about a tubular guide 106 and acting between a cup-shaped member 107, Fig. 1b (not shown), integral with the breech body 34 and pins 110 belonging to a plug 109 rigid with guide 106 which is held in position by a bayonet joint, pins 110 co-operating with groove 113 provided in block 79 and locked in position by spring- loaded levers 108, the ends of which co-operate with two recesses 111 in the block 79. A fourth mechanism for resetting the gun is housed below the right-hand slideway and comprises a chain 114 guided in a tube 115. A pin 116 mounted on a spindle 122 which is rotatable by a handle 123 is in mesh with the chain so that rotation of the handle causes the chain to be pulled rearwardly for resetting the gun or to be pushed out of action. A slider 120, Fig. 6 (not shown), connected with the front of the chain is adapted to come into contact with a hooking projection 121 carried by push-piece 64 of the breech body. An ejector mechanism is housed above the two slideways and comprises an ejector 126 slidable on two rods 127 and biased by damping springs 128. The ejector passes through a recess 34j in the breech body to act on the cartridge cases which have been extracted by extractor 125. A rod 129 moved forwardly against the action of spring 130 by the feed mechanism stops the gun after the last shot by causing breech body 34 to be caught by sear 94. The gun is fired by a trigger mechanism supported by spindle 122 which actuates sear 94 to release the breech body 34 which is driven to the front by spring 105 and pushes a cartridge into chamber 53. Once the breech body 34 has reached its front position firing pin 35 which was held towards the rear by locking members 40 is projected towards the front by its insertia and spring 36. By contact of oblique faces 44, Fig. 13 (not shown), with faces 43b the firing pin drives the locking members 40 outwardly and passes between the locking faces 43a of the members 40 which engage in recesses in arms 5a to lock the breech body in position. The firing pin is thrust to its front position to fire a cartridge by the mass of plug 38 moving against spring 36 and also floating member 39. After firing of a cartridge powder gases act through passages 52, 51 on a piston 56 which first acts on push-piece 64 engaged in groove 66 of the firing pin to push back the latter and then the piston 56 acts directly on the breech body to move it rearwardly. At the rear of its stroke the breech body contacts and compresses spring 140 which sends it back towards the front. Firing being continued until the trigger is released. The barrel is releasably secured by a bayonet joint to a sleeve 5 in turn secured to the breech casing by split ring 10 and screw-threaded plug 12, the barrel, sleeve and breech casing all recoiling on each shot against springs 17 which act between shoulder 13 of sleeve 5 and a strap 16 secured to a fixed support 22 by two vertical spindles projecting through elongated guiding slots in breech casing 1. The feed mechanism need not be fixed to the breech casing and so recoil therewith but may be rigid with the fixed support 22 in which case the drive between the sector 90 and the feed lever is of such longitudinal length as to be operative during relative movement of the parts.