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To Crimp or Not To Crimp?

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12 January 2003, 08:31
Mule Skinner
To Crimp or Not To Crimp?
I am loading 180 gr. Partitions for my Winchester Model 70 in .300 Weatherby. I am wondering how many of you would crimp bullets on this round. I am wondering if the recoil will set bullets back in the case or force them out of the case into the magazine well. If you crimp, is the Lee factory crimp ideal for this? Thanks, Dave

[ 01-12-2003, 01:37: Message edited by: Shark Bait ]
12 January 2003, 11:18
BossMoss
If you go to the Accurate home page and look under FAQ there is a study done on crimping useing the Lee fartory crimp die. He used 3 different loads and accuracy was better in every one useing the crimp die so I don't think it will hurt but most will tell you not to though.
12 January 2003, 12:03
RIP
I always like to crimp a hunting bullet if I can.

The recoil forces will batter the noses of the bullets, and any movement ought to be into the case if there is any movement at all.

A light kicker like the 300 Wby probably wouldn't be enough to dislodge a good non-crimped seating, unless that is a flyweight rifle. [Wink]

A full case of powder (100% loading density) and no crimp would be a good way to go if that is what your rifle likes best. That will usually mitigate any movement of the bullet deeper into the case.

I would still prefer a 100% load and a crimp in a hunting rifle, if possible.
13 January 2003, 01:01
<Reloader66>
Only heavy recoil rifles need the bullet crimped in place. Ammo subjected to rough use should be crimped in place. Only bullets with a crimp groove in thier jacket should be crimped in palce. My best accuracy is acheived with the uncrimped bullets. Their is plenty of bullet baring surface to hold the bullet in place on a 300 Weatherby magnum case. Another myth about bullets is deformed bullet points do not effect the accuracy of that bullet. Testing has proven that a bullet with a severely deformed nose will still strike point of aim. Bullets with minor nicks or damage to the rear of the bullet will fly off point of aim. Every bullets center of stability is maintained at the base or rear of that bullet. I have conducted my own tests and found this to be true.
13 January 2003, 02:23
John Frazer
quote:
Originally posted by BossMoss:
If you go to the Accurate home page and look under FAQ there is a study done on crimping useing the Lee fartory crimp die. He used 3 different loads and accuracy was better in every one useing the crimp die so I don't think it will hurt but most will tell you not to though.

The only time I've tested this semi-seriously was a reduced load for the .338 Win. Mag. -- I thought that with the case only half full, a crimp might ensure better ignition. It seemed to do that, with lower SDs for the crimped loads, but accuracy wasn't as good.

If I were testing again I'd measure neck wall thickness to rule out that factor. I'd bet that cases with inconsistent necks would suffer more from crimping.

John
13 January 2003, 04:20
<MRMD>
For hunting ammo, I recommend a crimp after having seen a bullet move in the magazine during an elk hunt. I use the Lee Factory Crimp die for all my hunting rifles.