1. A RECOILLESS GUN INCLUDING IN COMBINATION; A BARREL; A SUPPORT MEMBER HAVING A FORWARD OPEN END AND AT LEAST ONE REARWARDLY EXTENDING LEG; SAID BARREL MOUNTED TO AND COMMUNICATING WITH SAID SUPPORT MEMBER FORWARD END; A PROPELLANT CHAMBER IN AXIAL ALIGNMENT WITH SAID BARREL AND HAVING A FORWARD OPEN END AND A REARWARD RESTRICTED OPEN END; AN OPEN ENDED PROJECTILE CHAMBER DISPOSED BETWEEN, AXIALLY ALIGNED WITH, AND ABUTTING SAID PROPELLANT CHAMBER AND SAID BARREL, SAID PROJECTILE CHAMBER PIVOTALLY CONNECTED WITH SAID PROPELLANT CHAMBER; AND MEANS FOR SUBSTANTIALLY SIMULTANEOUSLY MOVING BOTH CHAMBERS LONGITUDINALLY REARWARDLY AND ROTATABLY AWAY FROM SAID BARREL AND ROTATABLY AWAY FROM EACH OTHER, SAID MEANS INCLUDING A FIRST PIN FIXED TO SAID PROPELLANT CHAMBER, A FIRST LONGITUDINAL SLOT IN SAID LEG ADAPTED TO PIVOTALLY AND SLIDABLE RECEIVE SAID FIRST PIN, A SECOND PIN FIXED TO THE FORWARD END PROTION OF SAID PROJECTILE CHAMBER, A SECOND SLOT IN SAID LEG ADAPTED TO PIVOTALLY AND SLIDABLY RECEIVE SAID SECONE PIN AND FURTHER ADAPTED TO GUIDE SAID SECOND PIN LONGITUDINALLY REARWARDLY AND ANGULARLY AWAY FROM SAID BARREL, A THIRD PIN PIVOTALLY INTERCONNECTING SAID CHAMBERS TO EACH OTHER, A THIRD SLOT IN SAID LEG ADAPTED TO PIVOTALLY AND SLIDABLY RECEIVE SAID THIRD PIN AND FURTHER ADAPTED TO GUIDE SAID THIRD PIN LONGITUDINALLY REARWARDLY AND TRANSVERSELY AWAY FROM SAID BARREL, AND DRIVE MEANS INTEGRAL WITH SAID PROPELLANT CHAMBER FOR IMPARTING A FORCE TO SAID FIRST PIN TO URGE SAME LONGITUDINALLY REARWARDLY IN SAID FIRST SLOT THENCE TO ROTATE SAID FIRST PIN IN SAID FIRST SLOT WHEREUPON SAID PROJECTILE CHAMBER, SUBSTANTIALLY SIMULTANEOUSLY WITH THE MOVEMENT OF SAID PROPELLANT CHAMBER, SLIDES LONGITUDINALLY REARWARDLY AND ANGULARLY AWAY FROM SAID BARREL AND PIVOTALLY AWAY FROM SAID PROPELLANT CHAMBER.