An automatic clutch is integrated in a weapon system between an ammunition feed system and a cannon. A feeder feeds ammunition into the cannon. The clutch mechanism includes an actuator, a locking pin with an assisting spring or the like, and locking cams. The clutch mechanism allows the drum shaft of the cannon to be disengaged from the gear of the feeder between the cannon and the ammunition supply system and thus from the conveyance mechanism of the feeder.