Following this thread I called Randy at RRA and he also agrees with you about headspacing when changing BCG or bolt so if you want to have a spare BCG or bolt, or try someone else's products what do you do? If gaged and it's a no-go,do you return parts,you can't always modify right?BCG for RRA is proprietary but he said check headspace anyway.So your not the lone ranger on this topic brother.Shoot on.