I've read through this post and wonder why I'm the only one that experience a difference every time! I switched in my 7 STW, my 26 Nosler my 30-378 and my 300 PRC each one I had a slightly higher velocity and flattened primers! I tried multiple lot numbers!
Don't feel alone. I have never had them shoot the same when I interchange them. In most cases, in my experience, the 215 group better than the the m's.
