Crimp or not ?

jmwyoming

Active Member
Feb 28, 2013
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Lost springs wy
Is it necessary or even recommended to crimp (roll or tapered) on my 300 weatherby mag. the rifle is a rem 700 classic in 300 weatherby. norma cases, 180 gr nosler accubonds. some say yes others say never. I would appreciate any advice you guys can give me, thanks, john.
 

Colorado Cowboy

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Jun 8, 2011
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Dolores, Colorado
First, the normal 2 die set that most reloaders buy/use, does not crimp during bullet seating. Unless you are using a tubular magazine, no crimping is really necessary. Crimping serves several purposes, first it seals the case to the bullet, especially in pistol straight wall cases (and some straight wall rifle cases like 45-70). It also allows more pressure to build up, which helps seal the case wall with the chamber preventing blowback. It also prevents the bullet from being pushed down into the case when loaded in a tubular magazine.

I don't crimp at all for any rifle loads, only straight walled pistol loads.
 

JimP

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Mar 28, 2016
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To decide if you even need a taper crimp or any crimp at all load you need to measure the length of your loads. Then load them into the rifles and start shooting. I'll keep the same 3 rounds in the rifle and load individual rounds into the chamber to shoot. Then after 3 or so rounds have been shot I'll measure the ones that are still in the rifle and see if the bullet has jumped further out under recoil. I usually only do this when I am changing brass, or the type of bullet that I am shooting. So far in over 40 years of reloading I have had no problem without a crimp but know of others that have had a problem.
 

JimP

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Mar 28, 2016
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Crimping will affect a lot of things. But if the expander ball is slightly oversize or if the bullets are slightly undersized the bullets may jump under recoil. That is where you need to load 10 or so rounds along with measuring the loads and load up the rifle and shoot it with rounds in the magazine of the rifle, to see if you are going to have a problem.