The Accurate Reloading Forums
Crimping
13 February 2011, 22:00
BCJamesCrimping
Just wondering what the consensus is on crimping. Right now I am seeing great accuracy on non-crimped loads, both barnes and berger, but I like the idea of knowing that the seating depth won't change with unanticipated rough handling (long range hunting load). Is crimping a hunting round a good idea? If so, what is the best technique for getting a consistent and repeatable crimp?? Thanks
13 February 2011, 22:17
GrumulkinIn most instances, crimping won't help accuracy in rifles with the probable exception of Barnes TSX bullets in my experience. I don't crimp cartridges such as 30/06 and 308 Win. but do crimp 300 Weatherby Mag. and 375 H&H Mag. cartridges to be shot in magazine fed firearms but some don't even crimp those. I've found it essential to crimp for a magazine fed 378 Weatherby Mag. if I don't want the bullets to move under recoil.
As for crimping method, I believe the Lee Factory Crimp die is the best way to go.
13 February 2011, 23:00
SamI don't crimp for rifle. Light crimp on pistol.
A bad day at the range is better than a good day at work.
13 February 2011, 23:06
vapodogThere are a few places where crimping is a very good idea.
1. Heavy handgun loads (especially for revolvers)
2. Tubular magazine rifles
3. Heavy recoiling rifles loads
With the revolver loads the recoil can actually force the bullet out of the case and lock up the revolver!
The last two categories should be crimped to avoid the foreward end of the magazine from driving the bullet back into the case.
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14 February 2011, 02:07
RandominatorThe only rounds that I currently crimp are for revolvers. I have done a couple of experiments involving crimps. First was a T/C Contender barrel chambered in a bottleneck revolver round. I worked up several loads using a couple of different bullets and several powders. At the end, I was getting accuracy of around 1.5" at 100 yards. These rounds had the bullet seated out about 1/4" past the crimping groove. I loaded some more rounds seating the bullet to the groove and applying a crimp. My accuracy went from 1.5" to over 3". This may also be partly due to the change to the round's OAL. The surprising thing was the change in velocity. The powder I was using was W296, which requires a heavy crimp in a revolver. In the Contender barrel, the velocity was slower and my ES went through the roof. No more crimps for me on this round.
My second experiment was with the 223 Remington. In my AR-15, 3 rounds would group .345" at 100 yards using Nosler 55 grain BT's. This is with a 20" heavy barrel and 4 x 12 scope. I tried some rounds using the Lee factory crimp die. My groups instantly went to over 1". I got the same results in a T/C Contender chambered in 223 also.
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14 February 2011, 02:41
wasbeemanI don't crimp rifle cartridges. That includes a .338 and a big 7 and a .300WM. Don't know that it would make a difference but I've never reloaded for any sort of automatic or the likes. Just bolt rifles.
Aim for the exit hole
14 February 2011, 05:02
plainsman456I have used the factory crimp dies on a 308 and it has made some difference at the target.
I use it on straight walled pistol cases but not on autos.
14 February 2011, 17:37
LabmanThe only rifle calibers I crimp are my 375 H&H and 416 Rigby. Everything else from .338 Win mag on down don't get crimped.
Tom Z
NRA Life Member
15 February 2011, 06:00
BCJamesThe two calibers that I am concerned about are 7mm Mag and 30-06.....so I guess no crimping. Thanks for the info.
16 February 2011, 06:00
Red C.Some people say that they get tighter groups using the Lee Factory Crimp die, even on light recoil ammo. Others curse the Lee Factory Crimp. For me, the jury is still out on this.
I do agree with Vapodog on where crimping is a good idea.
NOTE: When I do roll crimp (bullets with a cannelure), I like to do it as a separate procedure. I seat the bullets, then readjust the die for crimping.
Red C.
Everything I say is fully substantiated by my own opinion.