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Crimping and Setback

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Crimping and Setback Empty Crimping and Setback

Post by j_unzicker Sat Apr 27, 2024 8:04 pm

I’m loading Zero 230 JHP at 1.215” and if I crimp more than .471 - .472, I experience some setback when I drop from the slide release (full mag = about .010 - .015, one in the mag = about .005 - .010). But if I  keep my crimp at that diameter, I get no setback with one in the mag and either zero or minimal with a full mag = .001.
Also, if I crimp more, the bullet shows more deformation than I like (after removing the bullet, not only can I see the line from the crimp, but I can also feel it with my thumbnail). 
I would like to crimp a little more (maybe .469 - .470), and from what I’ve been reading it seems like most people can get away with a crimp like that on a JHP without deformation or setback. The reason why I would like to crimp more is because at .471-.472 about 1 in every 20 rounds won’t pass the plunk test in my gun. 

Am I missing something or doing something wrong?
Thank you.

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Crimping and Setback Empty Re: Crimping and Setback

Post by james r chapman Sat Apr 27, 2024 8:57 pm

Maybe full length size before loading powder and seating  bullet.
Case tension should prevent setback with those crimp dimensions
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Crimping and Setback Empty Re: Crimping and Setback

Post by j_unzicker Sat Apr 27, 2024 10:21 pm

james r chapman wrote:Maybe full length size before loading powder and seating  bullet.
Case tension should prevent setback with those crimp dimensions
My RCBS Carbide Resizer is set to touch the shell holder and sized cases seem to be spec. 
I’m wondering if my seater is the problem. It’s an old RCBS die from 1980. The box says 45 ACP, but looking inside the seat die, I can see a clear ledge. Maybe they only made roll crimp dies for the 45 ACP back then. I’m also using range brass, so various head stamps. I’ve noticed after resizing, case length can vary by .002” or .003”. That being the case, if I’m using a roll crimp die (set to taper crimp), wouldn’t that change my taper diameter by several thousands, based upon case length?

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Crimping and Setback Empty Re: Crimping and Setback

Post by BE Mike Sun Apr 28, 2024 8:44 am

j_unzicker wrote:
james r chapman wrote:Maybe full length size before loading powder and seating  bullet.
Case tension should prevent setback with those crimp dimensions
My RCBS Carbide Resizer is set to touch the shell holder and sized cases seem to be spec. 
I’m wondering if my seater is the problem. It’s an old RCBS die from 1980. The box says 45 ACP, but looking inside the seat die, I can see a clear ledge. Maybe they only made roll crimp dies for the 45 ACP back then. I’m also using range brass, so various head stamps. I’ve noticed after resizing, case length can vary by .002” or .003”. That being the case, if I’m using a roll crimp die (set to taper crimp), wouldn’t that change my taper diameter by several thousands, based upon case length?
I'd change to a dedicated taper crimp die and crimp as the final separate step to your reloading process.
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Crimping and Setback Empty Re: Crimping and Setback

Post by SingleActionAndrew Sun Apr 28, 2024 2:20 pm

Your COAL variation is normal and expected as we aren't seating off the bullet tip, and the ogive (where we seat with JHPs or FMJs) to tip distance will naturally vary between bullets even of fine quality within the same lot & box.

No need to crimp more than 0.470" with jacketed to my knowledge. (Lead is different). You don't need to crimp so much to be deforming your 230gr Zero JHPs, certainly not to an amount you can feel on a pulled bullet. I've loaded quite a few of those with success.

With mixed brass and small enough sample size this could all come down to brass rather than crimp variations. A taper crimp should only touch the forward edge of the case and not compromise the bearing surface or friction and waist neck tension from an adequately sized case I'd think.
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