Originally Posted by kepp
So, two questions:
1. I need to buy .224 bullets and not .223?
2. Does the 7 1/2 vs. 6 1/2 primer difference only apply to AR-15 style guns, or all 223/556 rifles?
1. You want a .224 bullet.
2. The difference in primers is two fold: for pressure and firing pin engineering. For 223, you'll want 7 1/2. 6 1/2 is probably safe, but is softer and meant for a lower pressure cartridge. AR's have a firing pin that floats which can also cause slamfires with softer primers supposedly. I would avoid the whole mess and just buy Winchester Small Rifle primers.