Crimp or not to Crimp?

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  • Crimp or not to Crimp?

    Should I be crimping? I would guess that with most loads, the case is full and there won't be much if any rooom for set back. Light taper or none at all? TIA
  • CoolBarrelBill

    #2
    I have never crimped just make sure you have enough neck tension about .002 minimum.

    Comment

    • sneaky one
      Chieftain
      • Mar 2011
      • 3077

      #3
      Try at least .004- .005 on the neck tension. I used to crimp on certain bullets,, yes they all can differ a bit on the outside diameters. The inside diam. of the brass after sizing, tells a tale too. Crimping on the 6.5 does'nt seem to do a lot to help with .264 bullets. I,, like a few others have tried the old .263 speer 87 grn. units. I did crimp them .,, at least for experiments sake.. If you can't get good neck tension with your die set,,,, time to move on to something better. You do not want the bullets moving forward during cycling,, hi pressure will result., and or bullets stuck in the throat= powder dump and -or more troubles !! Use quality equipment, and polish up your techniques. Measure 10 times , before you decide your next move. If you have a sh--ty die set===== let it go. I use the Forster ultra die set for Lap. and Horn. brass. I polished the inside expander ball down to .2595... It came to my door, at .2666. Would'nt hold a bullet too tight! I have the old lee die set too, Internally polished to a smaller size, I use it for the wolf brass, & ( sellior & bellot, F.C. and a few others, all in fireformed 7.62x 39 brass)) No need to crimp if all the specs. are correct.

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      • #4
        I noticed that on my last batch of loads, despite all the brass being from the same lot, being reloaded for only the 2nd time and given the same anal treatment, resistance to seating would vary from round to round, albeit slightly. To me, that means the neck tension is not consistent. Because of that, I gave all of them a pass through my Lee Factory Crimp Die, but with just a minimal amount of added crimp. I had to look closely with my magnifying visor to see it. Since I didn't conduct any scientific A/B test with a lead sled to see if there was a group difference, it's hard to say if it helped.

        Hoot

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        • LRS_Ranger

          #5
          I don't crimp my match rounds, to include my Grendel ammunition. I have never noticed any setback, and I'm getting pretty good SD, so I haven't messed with it.

          Comment


          • #6
            I don't crimp rounds. I use a slightly undersize expander ball to increase neck tension. Crimp tension relies on overall case length, AND length to the datum line on the shoulder that actuates the Lee crimp die mechanism. If either one of those things is different, then the crimp tension will vary from round to round. Varying neck tension will, of course, have an adverse effect on pressure levels, and therefore accuracy.

            In my 5.56 rifle, I have had only one round out of the last 10,000 loaded where the bullet got pushed further back into the case causing a jam. I don't know if it was a loose neck, or just one of those freak jams that happens once in a while...but it sure doesn't happen often enough for me to worry about when comparing it to the improved accuracy from not crimping.

            If I had a full auto rifle, then I would probably crimp though. I would also live with the reduced accuracy caused by the crimp.

            Comment


            • #7
              Originally posted by noone View Post
              I don't crimp rounds. I use a slightly undersize expander ball to increase neck tension. Crimp tension relies on overall case length, AND length to the datum line on the shoulder that actuates the Lee crimp die mechanism. If either one of those things is different, then the crimp tension will vary from round to round. Varying neck tension will, of course, have an adverse effect on pressure levels, and therefore accuracy...snip...
              I must have a different Lee FCD or else they changed them since yours was made. Mine is actuated by the bottom of the collet in the die being pushed up by contact with the face of the shell holder. Contact with the case is not needed to actuate it. Obviously it acts upon the neck, but to my knowledge, that is the only place on the case it contacts and then, just upon constriction at the end of the stroke. I've had some calibers where I use the Lee FCD to put a "hard crimp" on a neck. This is not the case with the Grendel. As I emphasized, it barely compresses the neck, just enough to hopefully give all the them a similar dimension, since without precision measurement and subsequent neck turning, there will be slight differences in the thickness and resulting tension from one to the next. You can feel it in the press handle. Not night and day differences, but differences all the same.

              Hoot

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              • #8
                Originally posted by Hoot View Post
                As I emphasized, it barely compresses the neck...
                Hoot, if you have a bullet puller, you may want to extract a few of those and check them. I have FCD's in both .223 and 6.5G, and some of my "lightly crimped" .223 loads had swaged the bullets out-of-round. Emphasis on "some"; I'm theorizing that neck thickness variations led to the inconsistent pressure.

                Comment


                • #9
                  Hoot,

                  You and I have the same Lee crimp die. Mine works the same way yours does. I'm just presuming that if the neck is longer from case to case, there will be more brass to grip the bullet, hence resulting in more force required to break the bullet loose from the crimp. I have no way to test my theory though.. I do know that crimping has always resulted in less accuracy even if I reduce the powder charge to compensate for the increased pressure.

                  I was incorrect about the datum line...my die actuates like yours does from the shell holder pushing up on the collet inside the die...sorry about that.

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