I`ve just had a couple case heads rip off, while competing with my M1A, costing me 2 misses, and blew my concentration. I`ve always used a Wison case guage, to make sure I wasnt bumping the shoulder back too far. Someone told me I should use the RCBS precision mic, to determine the ACTUAL headspace of my rifle, and go by that, not the Wilson guage. Does anyone use this method, and if so, how much do you bump the shoulder back from your chamber reading? Does it prolong the life of the case, and prevent head seps? Thanks guys-