Recording Crimp in reloads

Discussion in 'Reloading' started by bedlam, Jun 22, 2012.

  1. bedlam

    bedlam New Member

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    ok, so i've been reloading for a couple years and getting comfortable with it. however, as I have been recording my load data for the different guns, I realized that there doesn't seem to be any description on crimping.

    In other words, how do I record how tight of a crimp I put on a setup? A roll-crimp, I can eye-ball the depth the roll goes into the canulure (sp?) of the bullet.

    But a taper crimp... Hmmm... I've started by getting a measurement of the case diameter after the crimp (I don't mix brass), so I'll see if this gets me what I want after a few different loads.

    Or should I do my test crimp and measure it by how many whacks it takes to pull the bullet in the bullet-puller hammer?

    Thoughts?
     
  2. BountyHunter

    BountyHunter Writers Guild

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    A "crimp" is not needed or desired for rifle cartridges. If bullet retention is an issue, you simply go to a bushing die with a tighter sizing of the neck.

    Roll crimps are the preferred crimp in heavy recoiling revolvers, while most cartridges for automatics use a taper crimp die.
     

  3. Kevin Thomas

    Kevin Thomas Well-Known Member

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    Personally, I'd recommend the Lee Factory Crimp Dies for really heavy recoiling revolvers, but aside form that am in agreement with BountyHunter. Taper crimps for semi-auto pistols, and no more than necessary to secure the bullet from movement during feeding. Aside from Tubular Mag rifles like the M94 or Marlins, rifles generally don't benefit from crimping, and most actually suffer a loss of accuracy.
     
  4. drbill

    drbill Well-Known Member

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  5. bedlam

    bedlam New Member

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    Thanks for the replies. Was looking for a way to measure the amount, rather than the type of crimp to apply.

    I'm not ready to invest in the precision crimp tool, yet. Was hoping to find a method to measure crimp so I can pass to a friend to reproduce a load, or even if I were to reload on someone else's machine.
     
  6. Bart B

    Bart B Well-Known Member

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    You can measure the force required to pull a bullet from a loaded round by making a simple tool. Put a bullet puller in a board clamped to a work bench top. Make something to hold onto a shell holder (spare ram for a press?) with a bucket attached to fill with weights. Put a sized case with bullet seated and crimped in place in the bullet puller, slide the shell holder onto the case rim, then start putting stuff in the bucket. When the weight finally pulls the case off the bullet, weigh the bucket and its contents and record the weight. Do this several times to get an average and spread of force needed.

    I've done this comparing crimped case mouths to uncrimped ones. Crimping rifle case mouths onto bullets tends to increase the force spread to get the bullet out; especially on bullets without cannelures. And crimping case mouths onto bullets without cannelures tends to unbalance them a little bit. That added variable tends to make ammo less accurate in proper tests.
     
  7. bedlam

    bedlam New Member

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    Bart, that is what I am looking for. Awesome idea. Now, here's another question....

    The only bullet puller I've used is the impact version. I don't suppose you have a recommendation for what you are using. I see several out there, but I've never used this other style, so I'm unsure on what would work over the others.

    Thanks for the help.
     
  8. Bart B

    Bart B Well-Known Member

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    I do have a recommendation. Get a collet die with 7/8-14 threads that's normally used in presses. Drill a 7/8ths inch hole in a 3/4ths inch thick board then put the bullet puller in it with lock rings on both sides of the board. Use a collet sized for your bullets. I've used one made by RCBS that works fine. Other makes are just as good.
     
  9. bedlam

    bedlam New Member

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    awesome, thanks again.