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Thread: Neck tension VS crimping

  1. #1
    Gunny Sergeant
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    Neck tension VS crimping

    Has anyone tested how varying these two methods effect accuracy? I am wondering if it would be worthwhile to buy a collet type crimp die for rounds I fire in a semi auto 7.63x51. I have tried crimping my Grendel ammo, and found that I have to reduce powder charge to offset the extra pressure caused by the crimp.

    The amount of crimp is dependent on a number of factors, so I think it is less precise than I like. I haven't found any significant shift in my bullets from cycling through the action, so going either way may not be necessary.

  2. #2
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    If what Lee says about crimp offered the slightest increase in accuracy everyone in the precision community would use it...Nobody does.
    The collet die is fine, but it is not a crimp die.
    A crimp does not increase pressure in a significant way.

    I shoot dangerous game bolt action rifles and don't ever crimp...Not even with my 416 Rigby and 400 grain bullets.

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    Drifter™'s Avatar
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    If you're experiencing a significant increase in pressure from crimping, you're likely overdoing it. I'll sometimes crimp if it enhances accuracy, but not with the mindset of firmly holding the bullet in place.

    I usually take a Lee FCD in a hand press to the range. If a load doesn't perform to my expectations, I'll try a light crimp.

    As an example, I stopped after 3 shots @ 100 with this uncrimped Grendel load in new brass:



    With the exact same load, I crimped the next 5 shots and this was the result:



    Similar load in 1x-fired brass did fine without bothering to crimp. This is 10 shots:



    I can't predict when crimping will and won't work, but it's not difficult nor expensive to test it with any given load.

    I suggest a crimp so light that you question whether it's doing anything at all. Let the group sizes guide you.
    Last edited by Drifter™; 04-05-2013 at 01:15 PM. Reason: correction
    Drifter™

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    The only crimp die I have used is the lee die that functions when the cartridge pushes upward, and a sort of collet pinches on a small crimp. the point about precision shooters is very good, and I don't crimp any of my precision rifles. I will try some Grendel ammo with a very light crimp.

    Thanks everyone.

  5. #5
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    Rob01's Avatar
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    If the bullet has a cannulare groove then you could crimp but I do t see how deforming the jacket of a match bullet with a crimp will make it more accurate. I will stick with neck tension.