Military-style semi-auto rifles seldom have firing pin retraction springs. If care is not used in assembling ammunition, a "slam-fire" can occur before the bolt locks. The military arsenals accomplish this using different techniques and components-including different primer sensitivity specifications-from their commercial counterparts. CCI makes rifle primers for commercial sale that matches military sensitivity specs that reduce the chance of a slam-fire when other factors go out of control. If you're reloading for a military semi-auto, look to CCI Military primers. Effective slam-fire prevention requires more than special primers. Headspace, chamber co Mfg: Sinclair International