Crimp Jump in 9mm Revolver?

[RETDOE]

Would crimp jump be more likely to happen with lighter bullets or heavier bullets? I've had several so called subject matter experts and have gotten both answers. I have experienced crimp jump in my 940, both times with factory ball 115gr. So after these experiences I pretty much stuck with 147gr. Haven't experienced any issues yet but recoil has increased with the heavier bullets. A SME that is an acquaintance commentated that physics would say it would be more likely with heavier bullets due to the increase in recoil. I do note that some .357 mag J frames come with an advisory not to use with bullets lighter than 120gr.

THOUGHTS?

 

[Hair Trigger]

Are you talking about setback, I assume so. Do you reset your die between loading the 115's and 147's for the amount of crimp? I'm also assuming a taper crimp and not a roll crimp. It could be as simple as insufficient crimp or neck tension on the lighter bullet. I'm thinking a lighter bullet would be more prone to setback if the issue is too light a crimp or too little neck tension. Heavier bullet would have less tendency to move due to inertia.

Where are you finding the cases with setback? Are they the top couple in the magazine? Do you replace the same round you've chambered for carry back in the top of the magazine every time or do you rotate the rounds? You can get setback by rechambering the same round repeated times, the bullet gets pushed back incrementally as it hits the feed ramp or chamber wall when being fed.

 

[Nevada Ed]

If you load,

you might try to find 9mm bullets that have a "Can" on them.

The Berry platted have almost a "Can" on them.
The old 1970's Speer JRN , actually had a real (38 spl.) crimp on it,
pictured in it's manual.

Good luck.

 

[BarryinIN]

FWIW, The only time I've had crimp jump was when shooting Blazer Brass 115 FMJ.
I usually shoot Winchester USA 115 FMJ or my hand loads using 125 or 140 grain cast bullets (Saeco #115 and Saeco #383) and never had a problem. The first cylinder of the Blazer Brass showed some jump, and the second was worse. I stopped using it then.

Edit: Ruger LCR snub.

 

[David Sinko]

I have a 940 and the only time I see crimp jump is when I use plated bullets. These can't be crimped too hard or they will end up undersized or the crimp could bite through the plating leading to all kinds of problems. I don't think I've ever had a problem with hard cast or jacketed bullets of any weight.

 

[Kp321]

The heavier the bullet, the longer the parallel section that is in the case. This longer section provides more friction area, friction is the only thing that holds the bullet without a crimp groove.

 

[RETDOE]

Thank you all, just for clarification to those who misread the op, I am referring to a S&W 940 which is a revolver

 

[Nevada Ed]

The problem with 9mm, copper/plated bullets, it that 95% of them do NOT
have a canalure on them.

With a revolver, a heavy crimp will not cause problems in a cylinder.
However, it can cause damage to the bullet and what follows.

You might try some lead coated bullets, that can take a crimp and still
work pretty good for target work.
With a revolver, OAL is no problem, just follow the manuals data.