One thing that I do stick to is: when loading for my M1A and AR I use 'military services' primers. Particularly in the M1A. My comprehending would be the 'civilian' primers are way too soft and boost the infamous 'slam -fires' Now I do use primer flatness as a manual https://andyurnsn.theblogfairy.com/31199363/a-review-of-federal-gm150m-primers