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Help on crimp and CoL please

Discussion in 'Reloading' started by Vatwo, Dec 28, 2012.

  1. Vatwo


    Nov 2, 2012
    Just started loading 9mm for use in the indoor GSSF league shooting paper targets at 25 yds max. I am new to reloading and am struggling with the crimp amount on the Hornday LnL press. Is it ok if the bullet can be turned some in the case after crimping? Seems if I try to crimp any tighter I start to crush the case. Also, how consistant should the Case Overall Length be? Seems mine are varying as much as 10 thousands. Is this normal?

    Thanks in advance,
  2. The bullet should not be able to turn inside the case. If it's that loose, it could possibly set back upon loading into the chamber. That would greatly increase pressure.
    Are you full length sizing your cases? That alone should eliminate any movement of the bullet by making a tight fit. The only other thing I can think of is you may be flaring the case mouth too much.

    The 10 thousands variation sometimes occurs. I think that all depends on the uniformity of the bullets and you really can't control that.
    Last edited: Dec 28, 2012

  3. fredj338


    Dec 22, 2004
    Make sure the szing die is screwed all the way down to the sheel plate. CHeck your expander dia, make sure it is not more than 0.354", smaller is better. Overcrimping can cause less neck tension, as you bow the case away from the bullet. Check your brass, some brass is thinner than others & w/ 0.355" bullet, you won't get proper neck tension, regardless of how much crimp you apply. Crimp just finishes the handload, it does NOT hold the bullet in place.
  4. PCJim

    PCJim Senior Member

    Aug 4, 2008
    Gary, you are experiencing a common misconception new reloaders have with the term "crimping" and the reloading of straight-wall cases for autoloaders. Crimping generally refers to imparting a very light turn of the case mouth into a cannelure (groove) in the bullet. When dealing with straight-wall autoloading cases (9mm, 40S&W/10mm, 45acp to mention a few), you do not want to crimp the case mouth into the bullet. You only want to remove the flare / bell that you formed on the case mouth so that you could begin to seat the bullet. If you attempt to squeeze the case mouth beyond removing the flare / bell, you will begin to squeeze the bullet and, as stated above, actually reduce the case purchase (grip) on the bullet.

    If you want to check your die adjustments using a caliper, measure the thickness of your case wall at the mouth and double it, then add the diameter of the bullet. This should be the outside measurement of the case at the mouth after seating a bullet.

    Further, you can check for adequate tension on the bullet by performing a benchtop test. Measure the COL of your finished round, press the nose of the bullet against a hard, firm surface such as your benchtop with adequate pressure, then remeasure the COL. It should not change.
  5. Zombie Steve

    Zombie Steve Decap Pin Killa

    May 31, 2007
    Old Colorado City
    Welcome to GT and GT Reloading.

    Good advice here so far.

    Easy check - size a case, then try to start a bullet in there. If it goes in, your problem is the sizer. You shouldn't be able to get a bullet in a resized case with your hands. Next, look at flare - you just need to open up the mouth a teeny bit so that you can start a bullet into the case. Don't overdo it. Taper crimp is just removing that teeny flare after the seating die has pushed in the bullet. This is easy to overdo as well. Use just enough so you can drop the cartridge in your chamber (take the barrel out of your gun first) and it sits flush or slightly below the barrel hood. It should fall out easily.

    Good luck!
  6. Vatwo


    Nov 2, 2012
    Thanks for the great advice and explanations. I was totally off base on the seating and crimping. I read the words of experience, readjusted some dies and all is working great. I shot my first reloads at the range today.

    Thanks for the advice all, it really helped out.