Patent GB-148022-A (GB)
Title: Improvements in or relating to breech mechanism for firearms
IPC: F41A19/30
Filed: 1919-05-20
Abstract: 148,022. Payne, O. V., and Auto-Ordnance Corporation. May 20, 1919. Machine guns. - Relates to guns designed to operate as described in Specification 14368/14, in which the breech-block remains frictionally locked during the high gas-pressure developed in discharge, but is unlocked when the pressure falls, and consists in providing (1) means for locking the breech-block in the firing position and firing the gun simultaneously, and (2) means for readily assembling and dis-assembling the parts without the use of tools. The invention is illustrated as applied to a pistol of the type described in Specification 130,678. The breechblock B, adapted to slide in the receiver R, has an enlarged rear portion slotted at 4 to receive the return spring S and the rear portion 18 of the firing-pin FM, and a reduced forward portion 5 slotted to receive the forward portion 15 of the firing-pin and the ejector-pin. On each side of it is an inclined slot 12, in which are adapted to slide the uprights 20, 20<1> of an H- shaped locking-member L, having an inclining cross-bar 21 adapted to slide in a slot 19 in the firing-pin FM, and inclined studs 22, 22<1> adapted to slide in inclined grooves 23<1> in the receiver R. The inclinations of the grooves 12, 19, and 23<1>, in the example shown, to a plane perpendicular to the bore, are 22, 10 and 45 degrees respectively, and are such that on discharge, the lock remains in immovable frictional engagement with the receiver during the initial high gas-pressure, but slides upwards easily when the pressure falls below a certain value. The parts are shown in Fig. 6 unlocked and moving rearwards, the lock being in its upper position, in which the studs 22, 22', are raised out of the slots 23' in the receiver, permitting the rearward movement of lock, block and firing-pin. At the end of the return movement under the reaction of the spring S, the studs 22, 22' ride down the slots 23<1> into the locking position and simultaneously the firing-pin FM is urged forwards by the inter-engagement of the cross-bar 21 of the lock with the groove 19 of the firing-pin, and strikes the base of the cartridge at the instant that the lock reaches its lowermost position. The firing-pin has a finger-piece 16 projecting through a longitudinal slot in the receiver, to enable the breech to be opened by hand; an extension 18 of the firing-pin closes the slot. At the rearward end of its travel, the breech mechanism is cushioned by a buffer D comprising a plunger 50 fixed to the receiver and a cylinder 52 slidable on the plunger, the space between the two being occupied by leather washers 53. The forward end of the cylinder 52 is preferably provided with an air-vent. The firing-mechanism shown is of the type described in Specification 148,023, and is carried in a frame F which may be slidden out of the receiver R after the spring-pin 56 has been depressed. When this has been done, the spring S and buffer D may be withdrawn after the portion 51 of the buffer has been pushed forwards out of its recess in the receiver, and the breech-block, lock, and firing-pin may then be retracted and removed, when the three parts may easily be separated. The pistol carries two handles II, H<1> shaped to the fingers. The forward end of the breech-bolt, and also the bore of the forward end of the receiver are only slightly larger in cresssection than the cartridges so that the tendency of the latter to jam during the feed-movement is avoided.