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Thread: Crimping below the case mouth

  1. #1
    Boolit Buddy curioushooter's Avatar
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    Crimping below the case mouth

    I've never attempted to crimp below the case mouth on any cartridge, though I have seen factory loaded ammo crimped this way. Is there a way to do this with typical dies for 38 special for example? A collet type die like the Lee factory crimp die for rifles might work. Anything like that for 38?

  2. #2
    Boolit Master
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    It would have to be done with some form or fashion of collet.

    A regular seat/crimp die just couldn't reach in and do that.
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  3. #3
    Boolit Master
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    I always thought factory wadcutters looked like it was crimped with a cannelure tool. The only way a collet would work is if it only crimped in a lube groove, otherwise you would be destroying the bullet.

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    Boolit Buddy BigAlofPa.'s Avatar
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  6. #6
    Boolit Bub
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    I haven’t seen a die available like you want but I have used a centerpunch to add dimples well below the case mouth to prevent round ball loads from migrating further into case.

  7. #7
    Boolit Master WRideout's Avatar
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    I think you may be referring to the cannelure that factory 38 wadcutters come with. Apparently it keeps the bullets from backing further into the case. As I understand it, WC cases can't be bought commercially, and have to be obtained by shooting WC ammo to keep the cases. I have seen advertised cannelure tools that can be used to put that ring into a brass case. I have only ever seen cannelures on pistol ammo. Rifle ammo will only ever have a crimp at the case mouth to keep bullets in place.

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  8. #8
    Boolit Grand Master
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    The "crimp" is a cannelure, rolled in the case just like a knurl. A tool like this; http://www.corbins.com/hct-1.htm
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  9. #9
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    I'm curious why you would want to crimp below the mouth. I've seen and have lots of .38 Special WC brass that has cannelures to prevent the bullets from being forced deeper into the cases but those aren't crimps. Factory wadcutter loads were available a long time ago when revolvers were used for Bullseye and other competition. If you're the only person handling your wadcutter ammo (i.e., not shipping it anywhere) the cannelure is probably not an issue. A roll crimp, if your boolits have a crimp groove, will keep the boolit from getting pushed in deeper and delay movement until the pressure builds at the same time.

    I have an old style race pistol from the PPC days that is a WC only gun and I also like to shoot wadcutters from my Trooper Mk III. Things I've learned over the years include that not all .38 Special cases are suitable for loading wadcutters. Some start getting thicker just below the location of a SWC or other normal bullet's base. Pushing a wadcutter past that point bulges the case so much that they won't chamber. Military .38 cases marked WCC seem to be the thickest. Other cases, usually those without a cannelure, don't get thicker until they get to the usual area for a web and those make the best wadcutter loads. My now discontinued Saeco No. 381 wadcutter mold, the first mold I ever used in the early '80s, has a crimp groove just below the square shoulder so that's where it gets a roll crimp.
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  10. #10
    Boolit Grand Master

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    Crimping below the mouth may take more force to accomplish as its a complete ring or vee bend compared to the forming the mouth in. Another concern is work hardening of the mouth with the added bend and force. The collet crimp die with the end shortened enough to lower it may work How long it will last with the added force and forming is a thing to consider.
    Sizing in a tube mid point is more a swaging operation than a crimping operation. Here your not just forming the mouth into the groove bullet but forming the ring into the groove and back out again. 2 tapered walls in and back out with the straight section above left. It can be done but may require some additional force and special tooling.

  11. #11
    Boolit Master KYCaster's Avatar
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    I'm curious to know why anyone would consider a cannalure necessary to prevent a bullet from being pushed deeper into the case in a revolver cartridge. If that were the purpose of the cannalure, why would Winchester and Remington find it necessary to put TWO cannalures on their wadcutter brass?
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  12. #12
    Boolit Grand Master
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    I've read that also to prevent "set back" the cannalure was for identification. Possible reason for 2 cannelures. Another thought; many tube magazine rifles were chambered for handgun calibers, and may have used a cannelure to prevent set back in the magazine?
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  13. #13
    Boolit Master
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    I've seen the cannelure on 45-70, 45 Auto and .380(?) where the cannelure would/should keep the bullet from seating deeper due to recoil or feeding into the chamber. I have also seen it on the .30 Special factory wadcutters, there was the S&W 52 chambered for .38 Special wadcutters. The S&W 52 ONLY used wadcutters if I remember correctly. I've also seen 'stab crimps' on various cartridges instead of crimping the case mouth. All to keep the bullet where it belongs in the case during feeding, firing, other handling, otherwise it would be an unnecessary manufacturing expense.

  14. #14
    Boolit Buddy
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    With 38 special brass, two cannelures indicates that it is "wadcutter" brass, in which the walls of the cartridge do not thicken up as much/as fast
    when you go lower/deeper into the cartridge.

  15. #15
    Boolit Buddy curioushooter's Avatar
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    For the record that lee die referenced before wont work. Spoke to lee about it. It would work that way for a 357 max case. But not for 38 or 357 mag.

  16. #16
    Boolit Master Moleman-'s Avatar
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    It will work, but not as bought. The length of the collet needs trimmed to bring the crimp section down to where you want it and the crimp width thinned a bit if you want it to look more like a cannelure. Here's a pretty good writeup on how to modify a Lee collet style crimp die. http://www.450bushmaster.net/viewtopic.php?f=5&t=685
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  17. #17
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    Somebody made a Cannalure tool for putting a cannalure on a bullet, adjustable for depth and height. Can't remember who made it, (K&M) maybe ? lost mine . But someone here has to remember.
    But I don't know if there would be clearance for the rim.
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  18. #18
    Boolit Grand Master
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    Quote Originally Posted by Walks View Post
    Somebody made a Cannalure tool for putting a cannalure on a bullet, adjustable for depth and height. Can't remember who made it, (K&M) maybe ? lost mine . But someone here has to remember.
    But I don't know if there would be clearance for the rim.
    See post #8...
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  19. #19
    Boolit Master Moleman-'s Avatar
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    The main issue with the Lee collet crimp die is that it's set up to do one length only. You can make spacers to adjust it a bit, but if I'm ever bored enough I'll thread the bottom of the collet or make a new one so that it has an adjustable length collet so you can put the crimp where you want it.
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  20. #20
    Boolit Buddy curioushooter's Avatar
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    I am aware of Corbin's tool. Like everything else Corbin, it has priced itself out of usefulness, for me at least.

    I spoke to Lee about cutting down the collet as posted. They say it doesn't leave enough length for the collet fingers to have sufficient range of motion to work properly. They said that 357 Mag is the shortest one they make for this reason (and why there is no 38 Special offering, which is the cartridge I want to do this with anyway).

    Perhaps it would work, and perhaps $15 is a reasonable about of money to spend to find out. I'll think about it an report back.

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