Patent GB-430493-A (GB)
Title: Improvements in or relating to automatic firearms
IPC: F41A5/18
Filed: 1933-12-16
Abstract: 430,493. Automatic firearms. WATANABE, S., 357, Roku-chome Kita-Shinagawa, Shinagawaku, Tokio. Dec. 16, 1933, No. 35496. Convention date, Dec. 30, 1932. [Class 119] The three pivot pins 34, 34<1> and 36 of a toggle-link mechanism for the breech-action of a gas-operated automatic firearm are arranged in alignment when the breech is closed, or with the central pin 34<1> depressed beyond the dead-centre position, the positive initial bending being given to the links by the forward movement of the gas piston 65, Fig. 3. The breechblock 4 is opened thereafter by the blow-back pressure. In the construction shown, the piston moves in a short open-ended gas chamber 10 disposed near the muzzle end of the barrel 1, and is connected by a rod 64 to an actuator 7 slidably arranged in the lower half 3 of the receiver. The actuator has inclined faces 7<a> which, when the piston is moved forward upon firing, engage with similar surfaces 6<a> of the crank 6 of the toggle-links, thus lifting the pin 34<1> above the dead-centre position. A return spring 50, having a guide 51 bearing against rims 73 of the receiver, bears against the rear wall of the actuator. In the breech-closing position, Fig. 3, this spring maintains the actuator in contact with an extension of the crank 6 and thus prevents any movement of the toggle-link mechanism. Upon breaking the links, the crank extension follows the forward movement of the actuator while a step 4<a> on the breech-block engages with and moves rearwardly the guide 51 thus compressing the spring 50. The rearward movement of the breech-block is limited by a leather cushion 52 which contacts with the rear wall of the actuator. The firing mechanism comprises a trigger 11 pivoted at 16, a sear 41 pivoted on a pin 42, a sear-operating link 12, a pivoted hammer 17, and a firing pin 31. The hammer spring 21 is mounted on a guide 22 which is pivoted at 19 to the hammer and passed through a hole in the sear. The spring thus urges the sear to its hammer retaining position, Fig. 2, the release of the hammer being effected by the link 12 mounted on the trigger. This link by abutting against the lower wall of the actuator, is also adapted to prevent firing when the actuator is moved slightly forward by a rotatable cam-shaped pin 8. The trigger also carries two arms 43 which are spring urged into engagement with notches in the breech-block when the trigger is released when the magazine is empty. In this condition, the forward movement of the breech-block is further prevented by a plate 39 in the magazine. A spring-urged charger-guide 24 is slidably mounted in the breech-block, the forward movement thereof being limited by the pivot pin 26 of a spring-controlled extractor 25 adapted to engage with the cartridge flanges. The cartridges are ejected by an ejector the near end of which is struck by the fore end of the guide 51 upon the recoil of the breech-block. The Specification as open to inspection under Sect. 91 describes also a rear peep sight which is mounted in a T-shaped slot in the receiver and is raised and lowered by rack and pinion mechanism. This subject-matter does not appear in the Specification as accepted.