texrider wrote:I have noticed a difference in the flattening of the primers in all the small rifle that I reload for the AR. I have only used the CCI 400 and the CCI BR4. The 400s will flatten out for me a lot more than the BR4s for the same load in whatever caliber I load them in. I did have one primer get pierced with a 6.8 SPC heavy load. So that could be a problem for you if go heavy in the 450.
When working up a load I always preferred 400's as the flattening of a soft primer is what I was told many moons ago was your earliest pressure sign.
Don't know if that's accurate anymore, but it works for me..... YMMV