1. AN AT LEAST PARTLY SELF ACTING GUN WHICH COMPRISES, IN COMBINATION, A BREECH CASING, A BREECH BODY GUIDED IN SAID BREECH CASING SO AS TO BE SLIDABLE LONGITUDINALLY THEREIN, SAID BREECH BODY BEING PROVIDED WITH A LONGITUDINAL RECESS OPENING INTO THE REAR FACE OF SAID BREECH BODY, CARTRIDGE FEEDING MEANS OPERATIVELY CONNECTED WITH SAID BREECH BODY, AT LEAST ONE LOCKING MEMBER MOVABLY CARRIED BY SAID BREECH BODY AND ADAPTED TO COOPERATE WITH SAID BREECH CASING, AT LEAST ONE CONTROL MEMBER SLIDABLE LONGITUDINALLY IN SAID RECESS OF SAID BREECH BODY FOR ACTUATING SAID LOCKING MEMBER TO MOVE IT INTO COOPERATING LOCKING POSITION WITH RESPECT TO SAID BREECH CASING, A CAP LOCATED OPPOSITE SAID RECESS SLIDABLY MOUNTED LONGITUDINALLY WITH RESPECT TO SAID BREECH BODY AND FREE FROM CONTACT WITH SAID BREECH CASING, ABUTMENT MEANS CARRIED BY SAID CAP AND SAID BREECH BODY FOR LIMITING THE REARWARD DISPLACEMENT OF SAID CAP WITH RESPECT TO SAID BREECH BODY, AND RESILIENT MEANS INTERPOSED BETWEEN SAID CAP AND SAID BREECH BODY FOR URGING SAID BREECH BODY FRONTWARDLY WITH RESPECT TO SAID CAP.