My fired cases are .585" at the base. After running them through the RCBS sizer, they are still .585". At first I thought this would be OK, like a neck die... unfortunately, after two firings I'm having very stiff bolt opening. So what's the problem? Tight chamber, slightly oversize die, both, neither? (My guess is that I have a tight chamber and a upper tolerance die.) Anyone have a set of dies with a tighter base?