Abstract: A rotatably mounted hammer lock member has a hammer stop abutment. The trigger rod has a first operating projection received in a recess of the hammer lock member such that a reciprocal movement of the trigger rod causes a corresponding rotational movement of the hammer lock member. An interrupter member is hingedly mounted to the hammer. A projection at the rear end of the trigger rod is loosely received in a recess of this interrupter member. The rear end of the trigger rod includes a chamfered control surface area. The frame of the gun includes a corresponding chamfered control surface area. When the trigger rod is moved by the trigger for firing the gun, it rotates the hammer lock member such that its hammer stop abutment will be moved out of the way of the hammer.