Redding Profile Crimp

[justindad]

To put my final conclusion first: I wish I bought the Redding seating & crimping die with the micrometer instead, which I have in .357 Mag. I do not seat & taper crimp in one step because the mouth of the case scrapes the bullet, but this does not happen when seating & lightly/moderately roll crimping into a cannelure in one step. A heavy roll crimp would be good to do separate from seating. The profile crimp die is better for the heavy roll crimp.
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I added the Redding Profile Crimp to my RCBS Cowboy dies in .45 Colt. Compared to the RCBS crimp & seating die, the Redding profile crimp die is able to put a much stronger crimp without bulging the case. So a good upgrade if a strong crimp is needed for magnum loads.
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This die will pull the bullet down into the case, shortening the OACL, when putting on a heavy crimp. I shortened one 0.015” without causing a bulge in the brass. The amount of change in the OACL could be one way to gage just how strong your roll crimp is, and keep the strong roll crimp consistent between set-ups.
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Here’s a picture of a very tight roll crimp without case bulge.

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Here’s an old picture (slightly different 255 grain bullet), where the RCBS bulged a case without nearly as strong of a crimp:

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Also, I have two dummy rounds - one has a strong roll crimp. I put the tightly crimped dummy round into the press and lower the profile crimp until it just touches the dummy round. Then, this crimp is set just right to remove the bell on the case without apply a strong crimp. This is a faster die set-up than I’m used to.
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If you do not full length size your brass, the bottom of the profile crimp die will size/polish your brass, shown by the shiny band in the lower half of this case:

[Wheelguns 1961]

I use the profile crimp dies on all of my revolver rounds. They are great. They give three different crimp profiles. The first, a light crimp, looks much like a taper crimp. Tighten it up a little more, and you get the roll crimp like in your pictures. This can be lighter than the one in your picture, or heavy like you show. For big heavy bullets in hard hitting calibers, you can tighten it up even more, and you get a crimp that looks like a collar around the bullet. This crimp resembles the buffalo bore type of crimp. This type of crimp is very effective at preventing crimp jump.

[justindad]

Where do you see crimp jump?
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Have you ever seen a problem from too much crimp?

[Wheelguns 1961]

Crimp jump has mainly been in 454 casull. However, it could also happen in any heavy recoiling load. I have had a 327 fed mag load jump crimp and tie up my revolver. If you use enough crimp to dig in to the bullet, you are using too much. Also excessive crimp will shorten your brass life. You have already mentioned the case bulging issue.

[justindad]

Thank you!

[Nueces]

I was an early adopter of the Redding Profile Crimp die for my revolver rounds and I agree that they work beautifully. I am also a die enthusiast, always interested in optimizing my dies. I found the Dillon AccuCrimp die to work as well as the Redding and the design allows in situ disassembly for cleaning on a progressive press without disturbing the setting. So, I use the AccuCrimp die in the Dillon 550B for my 45 Colt cowboy loads.

[Char-Gar]

I would call that a Godzilla crimp and have never needed anything that drastic. I wonder what would happen to an alloy bullet having to straighten that out to escape from the case.

Is the idea behind that much crimp, to prevent the rounds in the cylinder from jumping the crimp, or the desire to hold the bullets in place in order for a slow powder to build pressure. In either case, I would think increasing case neck tension would be a better way to go than a Godzilla crimp.