9mm Crimp Jump in revolver

Discussion in 'Ruger Revolver Forums' started by Buckshotshorty, May 31, 2015.

  1. Buckshotshorty

    Buckshotshorty New Member

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    Hello all:
    I recently purchased a 9 mm Ruger Light Compact Revolver (LCR ) and have since been reading about a phenomenon called "crimp jump" that occurs when a round such as 9 mm, which has essentially no crimp and is typically fired from an auto pistol, is fired from a revolver. The bullet jumps the crimp as recoil causes the case to back away from the bullet. In the extreme, the bullet can be moved forward enough to bind the revolver's cylinder from rotating.
    So, equipped with some reloaded ammo, and some Hornady Critical Defense and Critical duty, and my micrometer, I set out to see if this phenomenon occurs with my carry and practice ammo.
    All rounds were measured for OAL before firing, and then I re-measured the OAL of the last round after firing the first four. The results surprised me. In every case the fifth chambered round was .020 to .025 longer than it started out. Eg the Critical Duty ammo started out with an OAL of 1.120 and after firing four rounds, the fifth had an OAL OF 1.145". The amount of increase was not perceivable to the naked eye with the factory ammo, but I certainly noticed it with one my reloads, which jumped double the amount as factory.

    Conclusion: whether perceivable or not, ammo meant for autos does jump crimp in a revolver. How much depends on the ammo.
    Solution: I now run a good roll crimp on any ammo designated to be used in my LCR 9mm, and Mark the box as such. I have not had a single problem with crimp jump that caused any stoppage so far. The roll crimp is just a precautionary measure. Now it's back to the range with micrometer in hand to see if the roll crimp fixes this issue. Meantime I must say I love my LCR 9mm and carry it daily.
     
  2. VThillman

    VThillman Active Member

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    Nice investigation process. I wonder if cannelured 9mm bullets are available anywhere.
     

  3. phideaux

    phideaux Well-Known Member Lifetime Supporter

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    Thanks,

    Let us know if that completely stops the jump.

    It should.




    Jim
     
  4. buster40c

    buster40c Well-Known Member

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    When I first got my LCR I had a jammed cylinder. Turned out one of the rounds had a cracked case which due to recoil caused the bullet to come forward from the casing which jammed against the frame. So much for a revolver doesn't have jams. I know that was a total fluke but just goes to show it can happen. I might just for the heck of it check my LCR 357 for problems you are getting. I don't reload but it would be interesting to see how the factory loads perform.
    Interesting to hear your 9mm are gaining OAL just from a few shots fired. That's telling me there is fairly stout recoil from the 9mm LCR. I wonder is the recoil of the 9mm more or less than a .38sp? I think it probably has more felt recoil than a normal .38sp.
    Thanks for the post and that is good example why we come to the forum.
     
  5. Tommycourt

    Tommycourt Tommycourt

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    I have reloaded a couple thousand of rounds of 9mm but they are all Berry plated round nose (115 grn.). I use the Dillon Square D reloader which is the cheapest progressive reloader that Dillon carries. When I check the COAL I measure @1.150. The Berry's are a plated round nose and there is no cannelure on the projectile. At the time I was shooting a Glock 19 and 26 gen 3's. I don't know if this will help you as I am not familiar with the Ruger 9mm. My Dillon makes a light taper crimp on the round. I might add that the crimp is very light. Hope this may help you.
    Tommy
     
  6. Buckshotshorty

    Buckshotshorty New Member

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    I too reload on a Square deal B . Now that you mention it, I believe you are correct in saying it imparts a taper crimp. However, the deeper you screw in the final die, the more taper crimp it imparts. If using either coated bullets or plated bullets, a strong taper crimp will peel the plating/coating and cause leading. Therefore, I will only apply more crimp to jacketed bullets.
     
  7. Tommycourt

    Tommycourt Tommycourt

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    I only apply a minimum amount of crimp to my Berry bullets as they are plated and the plating is not real thick. You want to be careful when applying the crimp so you won't be peeling the plating off when the round leaves the chamber. I have checked my loads by using a bullet puller and you can barely see the crimp I put on. It's just enough so when I push the loaded bullet down on my bench, there is no movement. Also Hornady calls their bullet a different name rather than call them plated, but they are a plated projectile regardless of the nomenclature they use. I think they call it a jacketed bullet. I would check a couple of bullets (w/o powder or primer) and see how much of a crimp mark you see on the projectile. You should just barely see a real thin line and not much more. All you are doing is simply sealing the cartridge around the projectile so there is no slippage. If you can move the projectile by pushing it on your loading bench, then increase the amount of crimp. You don't have to push hard, just exert a little pressure.
    Tommy
     
  8. MagBlackhawk

    MagBlackhawk Patriot

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    Considering today's political climate I switched to factory ammo in my 4" barrel 357. I checked Hornady CD and Win. PDX1 125 gr ammo.
    The bullets moved some on the 5th and 6th rounds with both brands. Not enough to pull the bullet, but you could see it with the naked eye.
    When I work out my handloads I always watch for bullet pull. Kind of a fluke that I checked factory loads.
     
  9. Tommycourt

    Tommycourt Tommycourt

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    Magnum,
    I have NEVER heard of a projectile proceding out of an unfired round. It's sounds impossible but I do believe every word you are saying. It's sure not the pistols fault, it's the ammo you have been using. A lot of ammo is made outside of the U.S. but I thought Hornady made all of theirs here. Winchester I think sends some outside the U.S. to have it made because the standards are different outside of our country and they can get away with making crap. Tulammo is one of them. I tried it ONCE and had a belly full of that crap. My suggestion would be to at least contact the manufacturers of both ammo and express your displeasure and state to them the danger involved of your circumstances. You have nothing to loose by trying!!!!!
    Tommy
     
  10. VThillman

    VThillman Active Member

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    Yeah, it's easy to see the change in bullet position when the crimp is in the cannelure. Your post makes me think that I have been screwing up by seating the .357 & .44 bullets so that the roll crimp is at the leading edge of the cannelure. I should be using the trailing edge, so the crimp has something to hang onto.

    Waxing philosophical regarding these non-cannelured bullets in straight-walled semiauto rounds that headspace on the case mouth... we may be stuck between a rock and a hard place. A roll crimp is probably a no-no, dunno about a hard taper crimp.

    Another ('thought' may be an exaggeration) about bullet movement in a semiauto... most of the recoil is in muzzle flip. Rounds near the bottom of the magazine won't 'see' much of that, so maybe most of the movement - if any - in those rounds should occur when they have gotten near the top of the magazine. That possibility rates a big 'so what', except that it's a different situation from that existing in a revolver cylinder.

    I could go on, but my head hurts now. Used to be, when I was figuring something out my brain would just get to feeling warm.

    :hammer:
     
  11. Tommycourt

    Tommycourt Tommycourt

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    When I was loading some lead rounds (RN 200 grn) I used the cannelure that was the farthest cannelure on the bullet.That was my .45 cal. When I loaded .357 (154 I believe or 158grn). flat nose I did the same. In other words, the last one on the front of the ojive (farthest from base of bullet) and I put a taper crimp on it. I still use the same pressure crimp on my Berry 230grn. RN.My crimp was never that hard, just enough to seal the projectile. I never had any problems but I was loading a medium charge.
    I hope this may be of some help to you guys.
    Tommy
     
    Last edited: Jun 1, 2015