That’s an excellent problem, Ted. I’m not sure. Here's a few samples of what I’ve heard in various locations around the Federal 210 vs Federal 210M variances: CCI 250 – Although not promoted as Element of CCI’s “benchrest” collection, several say these primers generate good consistency for your magnum rifle. https://are-federal-primers-good25789.dreamyblogs.com/32191002/rumored-buzz-on-federal-primers-gm210m