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I currently have the ABC's of loading, the Hornady 8th edition, and the small Lyman's "Load data" books for Auto loaders (9mm) and Popular revolvers (.38 .357). I still feel like I do not fully understand all the ins and outs of crimping. I have not had any of my .357s "back out" as it where, so I think I am doing that correctly. But if I understand correctly, when I start reloading for for 9mm I need to be concerned with how the crimping may affect the head spacing. If you guys had any suggested reading, that goes deeper into crimping, I would appreciate it. If the book also discussed matching powder burn rates to projectiles that would be a plus.


Thanks!

The thing to be careful of is that you don't roll the case mouth in smaller than the throat of the chamber. You can make it squish so tight that the case sits forward into the chamber, instead of being held back by the edge of the brass.

Does that mean I should be able to check the chamber measurements with my micrometer against my crimp? If that is the case, would it mean that as long as the crimp measurement exceeds the chamber measurement, and the round chambers correctly, I am ok? Is there a magic measurement for the crimp?

You should be able to drop a loaded round in and see that it's not in too far based on the barrel hood/case relationship.

You also don't need to crimp them so much that it rolls the case inward. Just a couple thou is plenty - and you can measure that with a caliper.

Flare the case mouth minimally to start the bullet seating; crimp minimally just to remove that flare. Crimping doesn't really retain the bullet esp in auto cals, it just is done to remove the case mouth flare.

Big bore revolver magnums, that's a different trip.

Thanks for the info guys!