The Federal primers are made from softer metals and so they use a far more sensitive priming combination than anyone else. (This is why the race gun shooters make use of them, their guns have incredibly mild springs which cause light primer strikes.) 223 Rem. They recommended CCI (tougher primers) https://federal215primers100count78901.ttblogs.com/11445443/the-2-minute-rule-for-federal-primers-gm210m