Crimping below the bullet ?


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joneb
February 3, 2007, 12:22 AM
Is there a handloaders tool for crimping straight walled cases just below the bullet?

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flutedchamber
February 3, 2007, 12:27 AM
I believe what you want is a cannelure tool, the same as used to roll a cannelure on a bullet. Before you try it on a case, I would call someone that makes the tool, like C-H, and ask them if it is safe to do so. It probably is safe, but I am no expert.

LHB1
February 3, 2007, 12:46 AM
Jib,
NOT necessary to crimp case below bullet. When you properly full length size straight pistol case, the sizing die reduces diameter of case to BELOW the bullet diameter. When you bell mouth and seat bullet, the upper part of case expands to hold the larger bullet BUT the case below the bullet is still smaller than the bullet and thus you get what appears to be crimping below the bullet.

Good shooting and be safe.
LB

Kimber1911_06238
February 3, 2007, 12:48 AM
You don't need too and it doesn't sound safe. I think that it would increase chamber pressure drastically, but I'm no expert.

joneb
February 3, 2007, 12:57 AM
I have seen this on various ammunition, and thought it was applied to reduce bullet set back for ammo used in tubular magazines or bottom feeders.

The Bushmaster
February 3, 2007, 01:06 AM
Now why would you want to weaken the case. Most splits and/or blowouts that I have had have been at the cannelure of a straight wall case.

Walkalong
February 3, 2007, 09:19 AM
The manufacturers use it to help prevent bullet setback on certain cartridges with certain loads. They do not know how many times someone will cycle it in their gun etc. potentially causing bullet setback and an unsafe rise in chamber pressure.:)

.010 shorter O.A.L. in some catridges can make a huge difference in pressure.

Geno
February 3, 2007, 09:31 AM
Check a factory .45-70 Govt. I never reconstituted the cannelure, opting instead to neck size only. It gave excellent accuracy for my Encore pistol. As I understand it, the cannelure keeps the bullet from setting back into the cartridge casing in a magazine. Of course with my single-shots, that is a mute point.

Jim Watson
February 3, 2007, 10:05 AM
Having seen bullet setback in .45ACP loaded with short bearing surface 185 gr JHP and everything possible done to increase bullet pull, I think there is a place for the below bullet cannelure.

My FLG was doing it with one of those C-H roller tools, because he had his own ideas about what a defense load should be. (The 185 gr Sierra JHP but at lower velocity than Cor-Bon which blows the bullet to smithereens in water.) That was slow and took a lot of care to get a whole box alike. So I designed and he built a tool that will do it in one stroke on a single stage loading press after the loaded rounds come off the Dillon.

Mal H
February 3, 2007, 10:32 AM
[caution - thread veer in progress]
Jim - a terminology question - FLG?

Jim Watson
February 3, 2007, 11:21 AM
Oh, sorry... Friendly Local Gunsmith
q.v. FLD, Friendly Local Dealer.

There are so many acronyms and initialisms on the Net that I thought I would contribute my own.

Walkalong
February 3, 2007, 12:41 PM
http://www.buffaloarms.com/browse.cfm/2,350.html

http://www.corbins.com/hct-1.htm

http://www.realguns.com/Commentary/comar47.htm

these might be what you are looking for.

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