First thanks for taking the time to help me' . I'm shooting a rem 700 5r 300wm. Nosler or Winchester brass, h1000, fed 215. I have no pressure signs in the head area, primers are not flat, no marks, I trim the brass to minimum. Extraction is smooth. Problem is I can't rechamber a fired case or it will stick in the chamber. 80% of the time, that puts neck sizing out. I try to just bump the shoulder a couple thousandths to head space on shoulder but the cases that won't rechamber after firing have to be fl sized with a heavy cam over just to get them to chamber at all. I want the brass to last as long as possible. Is there something I should be measuring that may have nothing to do with shoulder area. The area above the belt is .311 to .312 I don't know what reamer specs allow in that area. Gun has less then 100 rounds, I can't see any carbon build up in the neck/throat area with bore scope. It would be much easier to minimally fl size instead of the Max I have to. Could diff hard ness of brass cause this? Or maybe my fl die or shell holder? When I have to do the hard can over fl size measuring from head to datum line is diff from case to case by a couple thousandths which is why I was wondering about brass hardness. Or it could not even be needed if the shoulder is not where the case prob is.