Factory crimps are around .055 to .060 and that's what all the reloading data is based on. The resistance when a shotgun shell goes off is the weight of the wad and shot and the crimp depth resisting opening. So John, you're right, the crimp depth does make a big difference in pressures. From what I've read on primers, the Federal 209A and one CCI primer [ CCI 209M ] are " hotter " primers - all the rest are pretty close to the same and shouldn't make a difference at the low pressures we're using. On another reloading forum the guys recommend if subbing a Fed primer for a Win or such to go down 1 grain in powder. I've never done it seeing how I usually have at least 5 to 10,000 Cheddites on hand, just saying what they do. Most of my reloading data shows Win or Rem primers and I've always used Cheddites [ because they're way cheaper ] with no reservations.
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Paul Harm
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