the trigger 20 to disengage the hammer 4 it is necessary to act on the trigger 20 and to move it fully as in fig3 to the displacement of trigger 20 corresponds a backwards displacement of the rod 18 the nib 24 of which acts against the extremity 21 34 the extremity 21 34 is therefore rotated and determines the disengagement of the opposed extremity 21 39 of trip lever 21 from the cocking tooth 15 as shown in fig3 thus the hammer 4 is freed and urged by its respective spring 10 by means of the cradle 11 is speedily displaced to strike a firing pin 3 and cause a shell to be fired in the barrel corresponding to this firing pin at this point the recoiling inertial forces and the forces acting thereagainst cause a displacement of the pendular element 26 which element limits the recoiling of the hammer and prevents its uncontrolled return into a cocked position this action of element 26 is effected in cooperation with the peg 28 positioned beside the cradle 11 on which rests the hammer 4 as shown in fig5 besides the prevention of the recocking of the hammer the rotation of the head 6 is also prevented and consequently the danger of an additional firing of the weapon once the counter recoil action is terminated the pendular element 26 urged by its own spring 29 returns to a rest position while with the return of the trigger 20 to the original position there occurs the disengagement of the trip lever 21 by the tappet or nib 24 of.