Patent GB-402073-A (GB)
Title: Improvements in or relating to firearms
IPC: F41A19/31
Filed: 1932-04-11
Abstract: 402,073. Automatic firearms. GROVES, W. W., 30, Southampton Buildings, London.-(White Automatic Gun Corporation; Portland, Maine, U.S.A.) April 11, 1932, No. 10348. [Class 119.] Relates to automatic guns of the type in which the barrel l and breech-block a, Fig. 2, make a short recoil movement together, the breech-block then recoiling alone under the action of toggle-link mechanism b, c. According to the invention, relatively large abutment surfaces are provided on the crank c and the receiver m, which interengage when the breech is closed, and the crank pivot pin c<1> has a clearance whereby the pressure received by the crank is transmitted to the receiver by the abutments alone. Further, means are provided whereby the breech-closure mechanism is released -for automatic opening only when the gas pressure in the barrel has fallen substantially to zero. In the form shown, the receiver m is grooved at m<11> to provide guides, for lateral ribs of the breech-block. To relieve the pivot pins a<1>, b<1>, and c<1> between the breech-block, link b, crank c, and receiver, the members b, c are provided with co-operating surfaces d, e, Figs. 7 and 8, and the crank is further provided with shoulders f, concentric with the pin c<1>, which abut against inwardly projecting shoulders on the walls of the receiver. The breech locking mechanism is released for automatic opening by a link g pivoted at c<11> to the crank c, the lower end of the link being associated with an actuator h. The actuator is slidably mounted in the lower rear portion of the receiver and houses a main counterrecoil or return spring i, Fig. 12, and an auxiliary spring i<1>. The spring i bears at its forward end against the receiver and at its rear end against the partially closed end of a tubular portion h<1> of the actuator. The spring i<1> is housed within a floating sleeve i<11> disposed within the spring i and connected by a bayonet joint to a stud i<4> fixed to the receiver. urged forwardly by a spring x<1> and is held in the retracted position by a vertically movable sear w which is lifted, to release the striker, by a bell-crank lever v with which the trigger The spring il bears against the stud i<4> at one end, and at the other end against a plunger i<3> which rests against a stock abutment k. The actuator also houses a pair of cushioning and breech-opening spring-pressed plungers j. In operation, the barrel, receiver, toggle-links and actuator recoil together until the actuator, the motion of which is cushioned by the engagement of the plungers j against a forward extension of the abutment k, bears against the said abutment. The subsequent recoil of the receiver effects the desired movements of the link g to release the toggle-links, which move into the breech-opening position by their own inertia. The rearward stroke of the receiver is limited by shoulders k<6> on the stock abutment k. The firing mechanism comprises a firing pin y and a striker x, which latter is cocked, on recoil, by the engagement of a cam x<3> thereon with a cam surface a<11> on the breech-block. The striker is mechanism engages. The sear is removably held in place by a lock plate w<11> and is guided, in part, by a stud w<1> extending therethrough. This stud forms an abutment for a spring mounted within a plunger w<4> disposed between the lever v and sear. The pivot pin a<1> is removably held in place in the breech-block by a spring-pressed pin t<1> whose spring t<11> bears at its forward end against a plunger t<3> engaging the extractor t. The breech-block also houses an ejector u and its spring housing u<11>. The crank pivot pin c<1> is held in place by a spring c' one end of which engages with and locks in place a screw plug r<1> forming a housing for the spring r<11> of a buffer r. This buffer cushions the crank, on recoil, by engaging with its corner s against a shoulder q on the receiver. Specification 4399/00, [Class 119, Smallarms], is referred to.