GB222156A - Improvements in machine guns - Google Patents

Abstract

222,156. Gray, W. March 22, 1923. Machine guns.-A fixedbarrel machine gun of the type in which the breechblock 24 is reciprocated by a rotary cam 50 has combined gas and spring means for rotating the cam during automatic working and independent means, such as a crank 62, for manually rotating the cam member. The cam is automatically rotated by a block 73 which is connected to the gas-piston rod 69 and has a pin engaging with a spiral groove 84 in a shaft 85 which drives the cam shaft 52 through a one-way clutch 92. On firing, the gases of discharge passing through a port 70 in the barrel 20 impart forward movement to the gas piston 68, thereby cocking a spring 78 and conveying idle movement to the shaft 85. When the cam 50 is freed by pressing the trigger 65, the spring 78 reacts to rotate the cam, the breechblock is retracted by the groove 49, and the firing pin 29 is cocked by a projection 51 on the cam. The firing pin is held cocked by a sear 38 which is pivoted to the breech-block so as to be automatically released when the breech-block returns to firing position and loads a cartridge C from the magazine 123. If a missfire occurs, a spring-controlled pin 76 on the block 73 engages a recess in a locking disc 57 to prevent rotation of the cam.