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Old May 4, 2011, 03:19 PM   #1
Join Date: April 27, 2011
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crimping a 308

I'm just starting to reload 308s and when reading the instructions on the rcbs dies it talks about if you want a crimp or no crimp on the dies. How do you know whether to crimp the shell or not? I'm using Hornady Match .308 168gr bthp projectile.
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Old May 4, 2011, 03:25 PM   #2
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My rule of thumb is... don't do it unless there is a specific reason to do otherwise. All my rifles are bolt action and there is no reason at all to crimp any of them. I hear some of the guys say that it's good to put a small taper crimp on them for semi auto rifles but I don't know anything about those. As long as my brass mouths are about 0.003" smaller than the bullet before I seat them, that is plenty of tension to keep the bullet in place.
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Old May 4, 2011, 03:31 PM   #3
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Maybe off-topic, but in the .307 Winchester (308 case w/rim designed for the model 94) that I'm loading tonight, they must be crimped else the bullets wind up in the cases with the powder!

I can't see a reason for crimp in a bolt action.
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Old May 4, 2011, 03:31 PM   #4
Marco Califo
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Crimp Rifle Bullets which have a crimping groove.

Crimp Rifle Bullets which have a crimping groove.

Crimped bullets should be used in auto-loaders to keep the bullet in placing during the working of the action.

If your bullets do not have crimping grooves, then you are loading for a bolt gun. In this case you can use a very little roll or taper crimp. Lee factory crimp dies are supposed to work for crimping bullets with out the cannelure, but this may compromise some bullets and Speer warns against doing this with their bullets.
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Old May 4, 2011, 05:09 PM   #5
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there is an ongoing debate --
to crimp or not to crimp

I do not crimp bottle neck cartriges, even if the bullet has a crimping groove
the neck tension is enough to hold the bullet, if it does not check the neck

there are times to crimp ( tubular magazines, very high recoil )
read your reloading manual

none of my bolt action or semi automtic rifles have any type of
problem with these uncrimped cartriges ( I have checked and measured )
( 223, 5.56X45, 7.62X39, 6.5X55, 303, 7.62X54R, 308, 7.62X51, 30-06,
7.92X57 )
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Old May 4, 2011, 05:46 PM   #6
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I don't crimp anything that's going into a bolt gun.

I crimp everything that's going into a lever gun.

It's simpler that way.
Dennis Dezendorf
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Old May 4, 2011, 05:53 PM   #7
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Properly neck-tensioned 308 cases need no crimp.
(And note that your match bullets have no crimping
groove anyway.)
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Old May 4, 2011, 05:57 PM   #8
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Marco Califo

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Is smog considered weather?:barf:

Just because a bullet has a crimping groove,(cannelure), does not mean it HAS to be crimped. In fact where that cannelure ends up means nothing to the final product, if it's above the mouth of the case, so what.

Bearol, you can't crimp those match bullets with the dies you have. You could invest in a lee FCD,(Factory Crimp Die), then you can force the mouth into the side of the bullet. That can cause damage to the jacket, BUT most say it does no harm.
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Old May 4, 2011, 06:11 PM   #9
William T. Watts
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If the bullet doesn't have a cannelure then don't crimp, I don't believe the Hornady match has a cannelure either. I only crimp for a lever gun, I notice someone loads for a 307, I happen to have one also and I do crimp those rounds! William
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Old May 4, 2011, 08:59 PM   #10
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Thank you for everyone's responses, they help tremendously. And no the bullets do not have a crimp cannelure.
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Old May 4, 2011, 09:29 PM   #11
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I don't crimp any rifle shells except for a slight taper crimp on my 30 carbine.

I've loaded thousands upon thousands of 308, 99% for competition in my or others, M1A or issued M14. I never crimped nor have I ever had a problem by not crimping.

Pistols yes, rimmed straight wall with a heavy roll crimp, semis like the 45 ACP, 9mm, 40 cal, I use a taper crimp.
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