Excuse my ignorance, but

[LPatterson]

Interesting reading but I just checked my Second Edition Lyman Pistol & Revolver reloading book and it shows the crimp (measured at the end of the case) at .380". All of my minor loads are set for that and I have not seen any setback or overpressure. Books are great tools and should be used for more than leveling tables.

[Flatland Shooter]

I understand the need to test things instead of taking another person's word for it. I'm that way, myself. Just call me Doubting Thomas. Having said that, this is an awful lot of work being expended toward "figuring out" something that really was figured out decades ago.

Heh, I'm self unemployed (retired) and enjoy fixing the unbroken, rethinking the figured out and solving the other mysteries of the universe in my ample spare time.

By the way, pulled my notes and from my last visit with Dillon, they recommend 9mm be crimped to a measurement of .377' to .380". The diameter of the case just above the extractor groove needs to be .391" or less for reliable feeding.

Bill

[GForceLizard]

I set up my taper crimp to give me 0.378" I needed -.002 to pass the case check gauge. I probably don't need any taper crimp for my gun, but I use the gauge to be safe. Use as little bell as possible on the expander. Lead and coated lead bullets will require more bell to keep from shaving the surface of the bullet.