45ACP 230gr crimp question

[gregj]

I recently switched from shooting (USPSA) Bayou 200gr SWC bullets to Zero 230gr FMJ bullets. One thing I noticed, I had to crank my RCBS taper crimp down a lot more (maybe 1/2 turn) with the 230s to get the same .470 +- .0005 crimp I've been using with the Bayous.

I'm speculating this is due to the softer Bayous taking the crimp easier than the jacketed Zero 230s, but thought I would run it by the brain trust here.

I'm using a LNL, with the Hornady seat/crimp die only doing the seating in station 4, and an RCBS taper crimp in station 5. Brass is mixed headstamp.

 

[Walkalong]

Yes, a harder bullet with more "re-bound" will take running the die down a hair more. I have three settings on my .45 crimp die. Lead, plated, and jacketed. they are all about a quarter of a turn apart from each other.

 

[gregj]

"Rebound" was the term I looking for. Thanks for the confirmation!!

 

[918v]

The reason you had to turn your die in more is because the 200gr SWC bullets are .452" and the 230gr FMJ bullets are .451". This causes a change in the geometry between the crimping shoulder and the case mouth.