GB567714A - Improvements in or relating to automatic or semi-automatic firearms - Google Patents

Abstract

567,714. Automatic firearms. SANDERS PRECISION ENGINEERING CO., Ltd., and SANDERS, T. F. April 27, 1943, No. 6645. [Class 119] An automatic or semiautomatic firearm of the recoiling-barrel type has the locking and unlocking actions carried out by three members, namely (a) a rocker on the breech-block engageable with an extension of the barrel to initiate barrel recoil (b) a pivoted catch in the barrel extension, engageable with a stationary part of the firearm to retain the barrel in its recoiled position while the block completes its rearward movement and (c) a pivoted catch, also on the barrel extension to hold the breechblock in its forward position in the barrel extension and displaceable on the first part of the recoil, to release the breechblock. The barrel 2, Fig. 2, is screwed at 4 into a barrel extension 3 working within the fixed shoe 1 of the firearm, the barrel having a lug 5 guided by a tubular magazine 6 and urged forward by a spring 7. The breech-block 8 has a semi-cylindrical top, with parallel sides and slide lugs 9 whereby the breech-block is guided in groove 10 in the fixed shoe 1. The barrel extension has an arcuate notch 14 engaging a rocker 12 pivoted on the breech-block at 13, and two pivoted catches 24, 17 under the influence of a single leaf spring 19. In the firing position, Fig. 1, the forward end of the catch 24 abuts against the forward end of a groove 23 in the top of the breech-block, thereby locking the barrel extension and breech-block together. In this position, the rear end of the catch 24 is located in a cam recess in the fixed shoe 1, and the rocker 12 is seated in the notch 14 on the barrel extension. The centre of curvature of the part of the rocker engaging the notch 14 is slightly below and rearward of the rocker pivot 13 to permit a slight movement of the breechblock, on firing, to facilitate extraction. The rocker has a pair of trunnions 15, one on each side, engaging cam grooves 16 in the shoe 1. When the weapon is fired, barrel and breechblock recoil together until the cam face 28 trips the pawl 24 to release the breech-block from the barrel extension 3, and the cam grooves 16 act on the trunnions 15 to withdraw the rocker 12 from the notch 14. The breech-block then retires faster than the barrel, which is restrained by the spring 7, and the pawl 17 on the barrel extension engages with a notch 20 in the shoe 1, thereby preventing return movement of the barrel until the pawl 17 is tripped by the camend 22 of the groove 23 on the breech-block, when the latter returns under the action of its recuperator spring (not shown) after pushing a fresh cartridge into positiop. Barrel and breech-block then move forward, aided by the spring 7, until the rocker 12 couples with the barrel extension, and the pawl 24 swings into the notch in the shoe 1, the block and barrel thus being positively coupled ready for the next discharge.