Patent GB-1209509-A (GB)
Title: Improvements in or relating to firearms
Inventor: CERMAK JIRI
IPC: F41A19/46
Filed: 1968-04-10
Abstract: 1,209,509. Firing mechanism. VYZKUMNY A VYVOJOVY USTAV ZAVODU VSEOBECHNEHO STROJIRENSTVI. 10 April, 1968 [13 April, 1967], No. 17190/68. Heading F3C. A trigger mechanism for automatic fire-arms providing for a single shot or a burst of shots comprises a carrier catch 11 for retaining the breech block carrier 13 in its rear position, a hammer 24 and a hammer catch 29 for retaining the hammer in its cocked position and a tripping lever 19 adapted for selective engagement with the cocked hammer to retain the cocked hammer, and is characterized by a switch 15 for changing from one kind of fire to the other, the switch including a stud 16 engaging the sear and carrier catch and including means co-operating with the tripping lever, the arrangement being such that in its " burst " position the switch keeps the tripping lever inoperative and permits operation of the carrier catch and sear, while in its " single shot " position it renders the tripping lever operative and renders inoperative the carrier catch and sear. In the embodiment shown in Fig. 3, shown with the catch in the " burst " position, the hammer 24 is held in its cocked position, after the rearward movement of breech carrier 15, by a notch 53 on the hammer catch 29 pivoted at one end on the trigger pin 3. The arm 14 of the carrier catch 11 abuts the lower part of the receiver 1 to allow the arm 14 to engage the breech block carrier 13. The switch stud 16 engages a slot 20 in the sear 6 to raise its toothed end 7, about the pivot 5 on the trigger, to engage the claw 7 with the extension 8 on the carrier catch 11. In this position of the switch the tripping lever 19, which is pivoted on the stud 16, does not engage the hammer stud 25. When the trigger is pulled the sear 6 moves forward, its tooth 7 rotating the carrier catch 11 to release the breech block carrier which, in passing the fore end 31 of the hammer catch 29 moves the latter to release the cocked hammer and fire the weapon, which will continue to fire until the trigger is released, allowing the end 10 of the carrier catch to rise and retain the breech block carrier in the rear position. When switch 15 is moved clockwise to the single shot position (Fig. 4, not shown) the movement of stud 16 depresses the sear end 7 clear of extension 8, and rotates the catch 11 to withdraw its end 10 from carrier 13 to allow the latter to move to its forward position. While the hammer catch 29 is now depressed to release the hammer 24, the tripping lever 19 pivoted on the stud 16 has moved forward to engage hammer stud 25 by the tooth 27. The weapon will thus not fire until the trigger is pulled to contact projection 22 on the lever 19 and raise the latter out of engagement with the hammer. The switch 15 then rotates, under the action of spring 7, back to its " burst " position. In a second embodiment (Figs. 5, 6, not shown) the tripping lever is pivoted on the trigger pin 3 and has an arm (56 which rides on a cam surface on the switch 15<SP>1</SP> when the latter is in " burst " position, but engages a notch in the switch, when in " single shot " position, to be positioned to engage a stop (35) on the cocked hammer.