Safety device for automatic firearms
The invention refers to a safety device to lock automatic firearms, specially for submachine guns working with the system of advanced percussion and which has been designed to avoid accidental shots under the supposition that an incomplete recoil of the breech block would be produced at the moment of striking or due to any other accidental reason. 
     The realizations known so far about these safety devices are mostly elements placed in the striking or cocking lever which are adapted to block the breech block in an indirect way, but which are inefficient to control the same, when casual movements are produced. 
     In other cases, the sear is placed, so that it could retain the breech block as soon as it would pass the feeding point which brings about the inconvenience of reducing the extent of its movement towards the breech, weakening the percussion capacity to the prejudice of its working reliability. 
     The possibility of using two simultaneous sears is also known, of which the one in front is for safety and the other one is placed in the rear, from which the firing is started, both being actuated by the trigger. This procedure has the risk that, on finishing a burst by releasing the pressure on the trigger, the breech block may be retained in the safety catch which produces the same energy loss to strike, as it happened in the previous case. Furthermore, this device does not strictly provide any safety to the weapon, since a shot can be fired by pulling the trigger. 
     The safety systems based on the presence of key actuation in the buttstock also have been deficient. If the gripped weapon is carried, the safety device is deactivated which brings about the risk that the breech block would casually move enough to reach a cartridge of the loading clip, carry it back to the breech, strike it and discharge it. 
    
    
     These inconveniences can be avoided by means of the design in accordance with the herein described invention, in which an example is given in the schematic and descriptive drawing, applied to an automatic weapon of the machine gun type, in which: 
     FIG. 1 represents a side elevation of the system at rest. 
     FIG. 2 shows the position taken by the safety catch relative to the retention notches provided in the breech block, in the course of its recoil, explaining how the recovery movement is interrupted that began at the wrong moment. 
     The neutralized safety catch appears in FIG. 3. 
     FIG. 4 shows the system when the weapon is ready to be fired. 
    
    
     Referring to the drawing, when the breech block 3 is in a position of rest, FIG. 1, the safety catch 1 is pushed slightly in a forward direction by the triggering hook 2 of breech block 3 and is free to pivot vertically. In this state, FIG. 2, when the breech block begins to recoil, the safety catch drops into various notches 4 which are distributed along block 3 in the best way possible, as far as their situation and number are concerned. It can be seen in FIG. 3 how the can 5 of the last notch for the safety catch depresses it farther than the previous notches and in this way, it is in condition to move backwards because of the presence of slot 14 and the action of the tension spring 6, being latched by its rear nose 7 under edge 8 of the partition which closes its housing. 
     When this operation takes place, the shoulder 9 of breech block 3 has already passed beyond the nose 10 of sear 13, fully guaranteeing that the safety catch will be released only when it has been released by the sear. 
     If the operator pulls the trigger 11, FIG. 4, he will push the sear 13 via the pin 12 which will then release breech block 3, causing its advance because of the passivity of the safety catch in a deactivated position; this advance lasts until the breech block would reach the breech, even in the course of its run, when the sear would have returned to its position of rest because the trigger has been released. 
     In this way, it is achieved that the weapon at rest automatically has a safety device which prevents the inversion of the breech block recoil, while such a safety does not at all exist, when the striking is completed, allowing the breech block to return from the firing position, free of any prevention.