Had my first crimp jump

[Walkalong]

Walkalong - please define the difference between a real cannelure and an imitation cannelure. By definition a cannelure is just a series of cuts or grooves regardless of their depth so I don't understand how you define an imitation cannelure and what difference do you believe an imitation cannelure makes, what effect does it cause?

A cannelure should have depth to it for the case mouth to roll into, just like a crimp groove on a lead bullet. The "index" marks on the X-Treme and Powerbond (Maybe others) bullets are simply that, reference marks, and are not a real cannelure.

Taper crimps are better on plated bullets, simply because a roll crimp can cut into the plating too easily without a cannelure to roll into.

You are of course free to disagree with that interpretation.


A cannelure on a jacketed bullet is definitely not cuts in the jacket. You Tube should have some good videos of how they are applied. They are pressed into the jacket and leave the marks and low spot for crimping.

 

[ljnowell]

A cannelure should have depth to it for the case mouth to roll into, just like a crimp groove on a lead bullet. The "index" marks on the X-Treme and Powerbond (Maybe others) bullets are simply that, reference marks, and are not a real cannelure.

Taper crimps are better on plated bullets, simply because a roll crimp can cut into the plating too easily without a cannelure to roll into.

You are of course free to disagree with that interpretation.


A cannelure on a jacketed bullet is definitely not cuts in the jacket. You Tube should have some good videos of how they are applied. They are pressed into the jacket and leave the marks and low spot for crimping.

Continuing On what Walkalong has posted above, roll crimping into the plated bullets cannelure can result in separation of the plated "jacket." This results in poor accuracy and possibly chunks of plating being left in the bore.


I am not guessing either, I over crimped berrys plated 125 grain hollow points in a 38 special loads. Accuracy was horrible and up close I had multiple holes where the playing was separating and hitting my target backer.

 

[Gearhead Jim]

FWIW-
For decades, my backup/OD/retirement gun was some kind of Airweight/Airlite J-frame. Latest was a 340PD Airlite at about 11 oz. My reloads use the Winchester 125 gr JHP bullet, like what they use in their factory ammo, and it has a real crimp groove.

Standard velocity loads don't pull the bullets in my Airlite.
Max +P loads don't pull the bullets in an all-steel 640.
But shooting the max +P loads in the Airlite will jump the crimp no matter what I do.

I'm using a Dillon sizer die that's tight enough to create loaded rounds which are slightly wasp-waisted, like most Dillon dies.

My expander is for a 9mm and slightly polished down.

I've tried all degrees of taper crimp and roll crimp; from virtually nothing to really turning into the crimp groove. There are differences, but I still can't fire 4 rds without the 5th jumping the crimp at least slightly. Once-fired Winchester brass.

The bullet "stretch" happens slowly, I can fire 8 rds (simulating a round getting cycled through twice) and it won't tie up the gun. So it's not an issue for my practice ammo. But making hot rounds that don't stretch at all in the Airlite is something I can't accomplish yet.