...These rounds will not chamber in my Stag Arms AR....
Out of curiosity, is the reason they won't chamber a problem w/ the cartridge base
or the fact that the case headspace
dimension was left too long? (Small base won't help you on that)
i.e., was the sizer die set up ~ 1/8th turn beyond shell-holder contact, ...so as to slightly "cam over"
on the ram stroke?