CCI # 400 = Small rifle standard primer. CCI # 450 = Small rifle magnum primer. CCI # 41 = Small rifle primer for ball ammo mfgd for 5.56 ball ammo. I know it probably has a thicker cup to prevent slam fires than the civilian primers. My question is chemically which one does it duplicate the standard or the magnum. I bought em because I thought they were equivilant to CCI 450 magnum primers. Anybody know for sure? Somebody has to know. I figured this would be the place to ask.