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 condition, firing pin shape and protrusion, bolt velocity, cartridge case condition, and other factors can affect slam-fire potential.https://www.brownells.com/reloading/prim...79079.aspx
I copied this from the above link.
This is why the imported Galils and some AK rifles from China had firing pin springs. Most commercial spec primers have thinner cups and are more sensitive, which can result in a slam fire when cycling a fresh cartridge.
Effective slam-fire prevention requires more than special primers. Headspace, chamber condition, firing pin shape and protrusion, bolt velocity, cartridge case condition, and other factors can affect slam-fire potential.https://www.brownells.com/reloading/prim...79079.aspx
I copied this from the above link.
This is why the imported Galils and some AK rifles from China had firing pin springs. Most commercial spec primers have thinner cups and are more sensitive, which can result in a slam fire when cycling a fresh cartridge.