Don't overlook the 64gr Berger. In my Shaw barreled 10FP I have shot the tightest groups of any rifle I've ever shot over a moderate charge of H-335. The 63gr Sierra is a close second in that rifle. For some reason that barrel prefers 63-64 grain bullets. As suggested, play with different primers once you get tighter groups and see what happens, but don't do this if you're loading to maximum charge weight without working up again.