Semi-fixed artillery round

Claim 1

A SEMI-FIXED, FIN-STABLIZED ARTILLERY ROUND COMPRISING: A CARTRIDGE CASE ADAPTED TO HOLD A PROPELLING CHARGE; AND A PROJECTILE ASSEMBLY ADAPTED TO BE FIRED FROM SAID CASE, SAID PROJECTILE ASSEMBLY EXTENDING PART-WAY INTO SAID CASE AND HAVING A PLURALITY OF PIVOTALLY MOUNTED FLIGHT-STABILIZING FINS AT LEAST PARTLY ENCLOSED IN SAID CASE; SAID FINS AND SAID CASE HAVING INTERLOCKABLE PORTIONS WHICH WHEN IN LOCKED ENGAGEMENT PREVENT MOVEMENT OF SAID PROJECTILE ASSEMBLY OUT OF SAID CASE UPON THE APPLICATION THERETO OF LONGITUDINAL FORCES LESS THAN A PREDETERMINED MAGNITUDE, BIAS MEANS CONNECTED TO SAID FINS TO URGE THE SAME IN ONE DIRECTION OF ROTATION SO THAT SAID INTERLOCKABLE PORTIONS ARE IN LOCKED ENGAGEMENT, SAID FINS BEING ROTATABLE IN AN OPPOSITE DIRECTION RADIALLY INWARDLY AWAY FROM THE INNER SURFACES OF SAID CASE; SO AS TO DISENGAGE SAID INTERLOCKABLE PORTIONS TO THEREBY ALLOW MOVEMENT OF SAID PROJECTILE ASSEMBLY OUT O SAID CASE UPON THE APPLICATION THERETO OF LONGITUDINAL FORCES LESS THAN SAID PREDETERMINED MAGNITUDE, TO PERMIT ADJUSTMENT OF THE AMOUNT OF SAID PROPELLING CHARGE.