I've never encountered factory crimped primers in Winchester commercial. Nor have I ever had any
overpressure/"belted" occurrences with the same Win ammunition. (at least the 180gr variety)
Methinks some of your "once fired" were in fact at 2x fires -- w/ the last firing being a handload using
either Lil-Gun or H110/296 --both of which give significant early extraction "belt" problems in ARs
FWIW: I moved from Starline
to Winchester brass after I looked at contributing factors in AR "belts"
https://thefiringline.com/forums/sho...7&postcount=42