Patent GB-1050054-A (GB)
IPC: F41A19/02
Abstract: 1,050,054. Trigger mechanisms. COLT'S Inc. Aug. 26, 1965 [Sept. 28, 1964], No. 36750/65. Heading F3C. A trigger mechanism for a gun includes a spring-loaded hammer 78 mounted for movement between cocked and firing positions and a spring-loaded trigger 34 for controlling the operation of the hammer and is characterized by a burst fire control mechanism selectively interconnecting the trigger and the hammer for automatic operation of the hammer to fire a burst of a predetermined plurality of shots upon a single actuation of the trigger. In the construction shown a pair of spring-loaded disconnectors 52, 50 (not shown), are mounted one behind the other on the trigger pin 36 in a well 46 in the trigger. A fire control cam 32 is provided which co-operates with cam followers 68, 66 (not shown), of the disconnectors 52, 50, the trigger cam follower 48 and the tail portion 122 of an automatic hammer control 118. The cam 32 is rotated from the safe position, as shown in Fig. 1, to single-shot, automatic and burst positions by a fire control selector 26. The hammer 78 is formed with a sear abutment 76 with which the trigger sear 44 co-operates and is connected through a helical spring 98 as a oneway clutch with a ratchet cam 86. The ratchet cam 86 has shallow and larger ratchet teeth, 88, 90. The hammer 78 is also formed with an automatic sear abutment 116 and a further sear abutment 158. The hammer is cocked by the reciprocation of the bolt carrier 22. When the selector 26 is moved to the single shot position the trigger 34 and the disconnector 50 are allowed to pivot while disconnector 52 is held in an inoperative position. On pulling the trigger 34, trigger sear 44 is disengaged from abutment 76 and the hammer 78 is actuated and then driven back by the rearward movement of the bolt carrier 22. The sear abutment 158 of the hammer then engages an intermediate sear 58 (not shown) of the disconnector 50 (not shown) to maintain the hammer in its cocked position. On release of the trigger 34 the abutment 158 and sear 58 do not disengage until trigger sear 44 and abutment 76 are engaged again. In the automatic position of the control selector 26, the trigger 34 and the automatic hammer control 118 are allowed to pivot while the disconnectors 52, 50 are held in inoperative positions. On pulling the trigger 34, the hammer is actuated and the bolt carrier 22 on moving rearwards to cock the hammer 78 releases the automatic hammer control 118 which has been abutting a shoulder 128 of the carrier 22 to co-operate with the automatic sear abutment 116 of the hammer 78. On the forward movement of the bolt carrier 22 the shoulder 128 again abuts the control 118 to disengage it from the abutment 116 when the hammer is actuated again. This sequence is maintained while the trigger is in its pulled position. In the burst position of the selector 26, the trigger 34, control 118 and disconnector 52 are allowed to pivot. A hook 108 of a vertically disposed pawl 106 provided on the disconnector 52 engages a tooth 90 of the ratchet cam 86 on pulling of the trigger 34 preventing clockwise rotation of the cam 86 while the hammer 78 is actuated. On the return of the hammer 78 by the carrier 22, however, the cam 86 is driven anti-clockwise by the one-way clutch connector, the hook 108 riding over the cam surfaces and co-operating with a tooth 88 while the control 118 engages the abutment 116. The firing continues as in the case of the automatic firing until a large tooth 90 is reached by the hook 108 when the disconnector is allowed to pivot sufficiently for its intermediate sear 60 to engage the hammer abutment 158 to terminate the burst.