My understanding is that CCIs are the hardest while Federals are the softest, don’t know how the other brands rate. But I’m more curious about which brand is the hottest, the hottest standard and hottest magnum primers. Still working on my 300blkout build and I’m just wondering if a hotter primer would give me a little more gas to operate my rifle. Anyone done or know of any primer testing to establish a rating? Thanks ahead.