GB872975A - Improvements in and relating to automatic firearms - Google Patents

Abstract

872,975. Automatic weapons. VERWALTUNGSGESELLSCHAFT -DER WERKZEUGMASCHINENFABRIK OERLIKON. May 22, 1958 [May 24, 1957], No. 16465/58. Classes 92 and 119. A fixed-barrelled automatic firearm has a breech-casing sleeve 3 in which slides a breech mechanism comprising a cartridge-obturating breech-body 4 in which slides a percussion striker 5 and a member guided by guide-faces in the sleeve 3 and controlling the locking in the firing position of the body 4 which is retracted after firing by a gas piston 10-11; the member being a transverse yoke 6 mounted in the striker 5 to be movable at right angles to the striker's motion, guided in oblique slots in the body 4 and by its ends in longitudinal slots 18 with enlarged front ends in the sleeve 3 and the breech body being locked by at least one locking body 13, mounted in the breech sleeve so that one, 13b, of its ends supports the breech body on locking and the other is controlled by, and supported in the locking position by the yoke 6. The members 13 are bell-crank levers pivoted to the sleeve 3 at 14. Figs. 2 and 4 respectively show the mechanism before locking and at the moment of firing, after which gas pressure on the cartridge-case bore causes inclined faces 4a on the body 4 to open out the locking bodies 13 so that the piston 10-11 can drive back the breech to eject the spent case, acquire a new round and reload under the action of the spring 7. Fig. 6 shows how the yoke 6 can move from the longitudinal portion of the slots 18 into their enlarged front ends 18b (Fig. 6, dotted line) whereby, whilst the body 4 moves forward a distance S, the yoke moves S + Z to lock the breech by pressure on the ends of the arms 13c. For this purpose the yoke has inclined frontfaces 6c which co-operate with the faces 17a of an inclined slot 17 (Fig. 6, full line) positioned transversely across the body 4 whilst the vertical end faces of the yoke are constrained by the vertical faces of a square slot 19 (Fig. 6, chaindotted line) positioned transversely across the striker body 5. Figs. 9 to 13 (not shown) illustrate a variation in which the locking bodies are semi-cylinders rotatable in semi-cylindrical recesses in the breech sleeve under the frictional control of spring-plungers set in the sleeve wall. In this version the end of the longitudinal slot provides for the yoke to rise, rather than fall, to engage holding faces on the flat sides of the semicylindrical bodies to turn them and lock the breech. As a safety measure the striker is hinged so that the firing pin is only aligned with the firing hole bush as the breech locks. An extractor (not shown) and an ejector are provided.