Another aspect of primer specs. Charlie touched upon is the hardness of the primer cup. In doing my research for my 22BR build and the the parent 6mmBR case over on 6mmBR website they had some suggestions about primers. The touched upon cup hardness of the CCI BR 4's and CCI 450's vs the Fed 205's. and hotter load use. I had found in my use that some loads that pierced primers with the Federals did not with the CCI BR 4's. The article
http://www.6mmbr.com/6mmbr.html
The statement: Primer Selection
CCI BR4s and 450s are giving the best velocities, with lowest ES, for the 100+gr bullets. For the shorter bullets, the Fed 205s work well. Federal 205s give good accuracy, but they don't handle high pressures as well as the CCIs, which have a harder cup. Stick to CCIs for hot loads.