Home Forums Reloading Big Game Rifles Cratered and Pierced Primers - Advice Needed

The chamber pressure of the .223 and the 5.56 are both 52,000 cup or 55,000 psi. The actual difference between the two is the throat and the shorter .223 throat will cause a pressure increase with military 5.56 ammunition.



The CCI 400 primers you are using have a cup thickness of .020. Just switch to a primer with a cup thickness of .025 and your primer problem will go away.



I would also advise using workup loads starting at the suggested start load and work up. This will teach you how to read your primers as the load increases.

Also your pierced primers are a sign you are bumping or pushing the shoulder back too far when sizing.

The primer after being hit by the firing pin will be pushed out of the primer pocket until it contacts the bolt face. This causes the primer to flow back over the firing pin and it can punch the center out of the primer.