to prevent firing of the primer by recoil or other shock the assembled shield 14 and primer 12 are press fitted into an appropriately enlarged cavity in the base of the cartridge 10 u2032 while this would require modification of existing cartridge bodies and changing of the primer cavity dimensions in new manufacture the existing large primers could still be used cartridge c of fig2 shows a variation of my invention in which the large primer cavity diameter of 0 212 inches is maintained in the cartridge body 10 u2033 and a smaller safety shield 18 is used to protect a u201c small u201d primer 20 which usually has an outside diameter of 0 175 inches again shield 18 has a center hole 22 with a diameter of 0 100 inches an inside diameter of 0 175 inches and an outside diameter of 0 212 inches these dimensions allow the primer 20 to be press fitted into the shield 18 and the assembly press fitted into the large primer cavity in the standard cartridge body shield 18 is preferably made of nickel plated steel with sufficient strength so the thinner wall will still protect the primer from firing it may be seen that in cartridge c the height of small primer 20 may be shorter than standard since safety shield 18 is sized.