I honestly don't know. A number of them listed I have never even heard of before.. I get from general reading on the web that, "military" primers made by CCI are the hardest and based on my personal observation this seems to be true. As I understand; CCI commercial is next, followed by Wolf. In a pinch, I have loaded for the Ar and the M1A using standard Winchester primers large and small. While I have never experienced a slam fire with them, the the dent left in the primer after firing the preceding round is noticeably more significant that any of the primers I mentioned above.