Patent GB-587368-A (GB)
Title: Improvements in or relating to automatic guns
IPC: F41A19/02
Filed: 1944-10-10
Abstract: 587,368. Automatic guns. JOHNSON, M. M. Oct. 10, 1944, No. 19473. [Classes 92 (ii) and 119] An automatic gun, capable of single-shot and continuous action, has a recoiling bolt, a hammer, a trip actuated by the counter-recoil of the bolt to release the hammer from the sear, and a catch for holding the bolt in its rear position when the trigger is released, the trip and catch being inoperative when the changefire device is set for firing single shots. The breech action is of the kind described in Specifications 486,907, 511,365 and 543,465, and the sliding bolt B, Fig. 13, is similar to that described in Specification 535,833, but has a pair of shoulders 23 to co-operate with the catch. The catch BC is pivoted to a catch support CS at 83 and is urged into operative position by a spring A ; a catch control CC, pivoted at 48, can be swung upwards by the trigger T to release the catch. The trigger, also pivoted at 48, is controlled by a spring 53. A pusher P is telescoped into the bolt, and carries a trip pin TP (Fig. 8), and spring buffer 43. The recoil spring RS acts .on the pusher. The hammer H, pivoted at 72, swings through a slot in the pusher to strike the firing pin FP, and a pair of inwardly projecting lugs 29 in the slot prevent movement of the hammer into firing position before the bolt and pusher are in their forward position. The hammer spring, HS, acts through a strut V. A tail 73 limits the movement of the hammer when the gun is stripped. The sear S, Fig. 23, is also pivoted on the pin 48, and has hooks 67, 68, for engaging with corresponding hooks on the hammer, the hook 67 serving to catch the hammer when the sear is in normal position, and the hook 68 if the sear is tilted forward (by the trigger), when the hammer is cocked. If the hammer engages hook 68 it shifts to hook 67 when the trigger is released. Pivoted to the sear at 94 is a sear trip ST, having a nose 96 for engagement with the trip pin- TP ; both sear and sear trip are in engagement with the spring 69 (Fig. 8), which urges them in an anti-clockwise direction. The action of the gun is controlled by the cam W, which can be rotated into three alternative positions by an external handle. In the locked position (Fig. 8) the cam (1) abuts against the rear face of the trigger and prevents it from being pulled, (2) permits the catch control CC to drop, so allowing the spring A to lift the bolt catch BC into position to engage with the bolt and hold it in retracted position and (3) allows the rearward extension 95 of the sear trip to drop, so that the nose 96 is out of the path of the trip pin. In its " single-shot " position (Fig. 9, not shown) the cam (1) permits the trigger to be pulled to its rearmost position, (2) raises the catch control CC, thereby swing- ing the catch BC to inoperative position, (3) allows the rearward extension of the sear trip to drop, so that the nose 96 is out of the path of the trip pin. In this condition the hammer is carried into engagement with the sear by the surface 121 on the recoiling pusher, and is held by the sear until the trigger is pulled again. In its "continuous" position (Fig. 10, not shown) the cam (1) permits the trigger to be pulled only sufficiently to close the clearance space between the top of the trigger and the bottom of the sear (see Fig. 23), (2) permits the catch control CC to drop, thereby allowing the spring A to move the bolt catch into operative position, and (3) raises the extension 95 of the sear trip, thereby moving the nose 96 into the path of the trip pin TP. In this condition, the short pull of the trigger which is permitted will raise the catch control CC sufficiently to. disengage the catch from the bolt; as the bolt and pusher move forward the trip pin TP catches the nose 96, thereby swinging the sear trip and sear clockwise against the action of the spring 69 and releasing the hammer. The gun will thus continue to fire until the trigger is released, when the catch moves up to retain the bolt in its retracted position. The cam is held in its alternative positions by engagement of a nose on the spring-loaded detent F with suitable recesses. A trigger release TR, pivoted at 62 and pressed by a spring 64, prevents the trigger from being pulled until the nose 63 is moved downwards by engagement of the hand with the projecting fingerpiece.