GB819228A - "automatic firearms" - Google Patents

Abstract

819,228. Automatic firearms. SCHWEIZERISCHE INDUSTRIE-G.m.b.H. April 15, 1957 [Aug. 28, 1956], No. 12244/57. Classes 92 and 119 An automatic firearm has a breech block assembly comprising a follow-up member 3, relatively movable in relation to a breech-head under the action of a mainspring 6, carrying a striker 4, and operating on a sear 15 which controls a hammer 23 urged by a spring 16. The breech-head has recesses 8 housing rollers 9 which may be forced out into locking grooves 10 in the weapon body by the conical front face of the member 3. The striker 4 is normally kept retracted in the member 3 by a spring 5. One arm 12 of the sear 15 slides in a groove 11 on the member 3 and another arm 18 presses on a pivoted, spring- loaded plate 20 which has a projection 22 to engage and releasably retain the hammer 23. In operation, with the breech fully open, the arm 12 is at the forward end of the groove 11 when the spring 6 starts to close the breech. After the breechhead 2 meets the breech face the member 3 continues forward and forces the rollers 9 into the grooves 10 to lock the breechhead. The arm 12 is then depressed by a projection 13 at the end of the groove 11 causing the plate 20 to pivot downwards and free the hammer so that it can pivot up into a relieved portion 26 and hit a projection 4a on the striker. Gas pressure from the fired cartridge presses back the breech-head and releases the rollers from the locking grooves, so that the breech block assembly can move back, depress the hammer, and repeat the firing cycle. Alternatively to the spring 6 a pair of springs, acting on either side of the member can be used.