Crimp v Velocity

[JoKeR338]

Picked up a Lee collet die and it came with a note talking up their crimping die (big surprise). I don't crimp, but they make some big claims such as better accuracy and uniform pressure/velocity.

I already searched the forum and read some crimping threads, however I want to know if anyone has put these claims to the test over a chrony and noticed decreased SD in velocity of crimped over non-crimped.

I'm not interested in ideas or theories of crimping or not, just actual experience between the two.

Thanks

 

[coyote_204]

A friend of mine tested it against a standard crimp and found Lee's taper crimp to be more accurate. He didnt shoot over a crony so I dont know about the sd. I personally dont crimp, so have never tried them myself.

Steve

 

[markley]

when i test a crimp i take my press to the range and start at the lightest crimp possible. crimp 3 and see how they group. if i get a group i like i crimp 2 more and see if they group with the pass 3 shots. when i adjust the crimp i barely turn it because the slightest turn really changes the amount of pressure.

 

[GC]

I use the Lee Factory Crimp die for all my magnum revolver and tube magazine lever gun cartridges. The Lee FCD works great in the .357, .41, .44 magnums and heavy loaded .45 Colt along with the .30-30 and .45-70. Never saw the need for it in any other loading I personally do for bottleneck rifle cartridges. As a note, I did test taper crimps against the standard roll crimp and Lee FCD with the heavy loaded .357 Magnum and found the taper crimp could actually be detrimental for strength of crimp power and was less consistent than the other two.

 

[ab_bentley]

It really depends on how well made your rifle/ pistol is. If it is a custom you probably see things go south when crimping. Crimping is another added measure to promote uniformity in a otherwise un-uniform chamber. The 22 Hornet in most factory bolt guns will see an improvment when using the crimp. A custom 223 with a semi tight neck you'll probably see groups open up when crimping. Proper neck tension will give you better results, whether that's with bushings or custom dies. Adam

 

[unloaded]

I tried the collet die and didn't like it. It doesn't cam over and stop like most dies do, The directions called for something like 25 ft/lbs of pressure. Kinda hard to get consistant results doing something by feel. Maybe if you replaced the handle on your press with a torque wrench you'd get better results.

If you just want a bit more neck tension and want it consistant polish the expander stem on your sizing die, the smaller you make it the more tension you'll get. I get really good results this way. Works best with boat tail bullets, flat base want to fall over going in the die.

peace.
unloaded

 

[JoKeR338]

Once again I want to state that I'm interested in experience of the Lee Crimp Die in regards to the claims they state.

If you have thoughts on the collet die or theory of crimping then by all means start a dedicated thread.

Thanks Coyote204 and GC for the info thus far.

 

[unloaded]

Sorry about my post. Not enough coffee in me when I read yours. I've only used the FCD's on pistol rounds myself.

 

[hickerx2]

I have extensively tested crimp vs. non-crimped. I found that there is not enough difference to bother. If your brass is prepped properly, you will already have uniform tension on the bullet.

I wouldn't doubt that there are applications where a crimp might be useful...like large cases full of slow powder.

Personally, I dont crimp anything but pistol/revolver rounds and rounds for my lever-actions. I dont even crimp my AR ammo.

 

[HOGGHEAD]

I believe it has alot to do with your cartridge of choice. Which you did not list. I have found that I get lower SD's(much lower) when crimping large caliber rounds with large bullets and slow burning powders. But I do not notice those differences nearly a much when I use a faster burning powder, or lighter bullets.

For exanmple. I load alot of 45 Colt. I found that with a heavy crimp my velocites are close to identical with a large charge of 2400(21.0 grains), and a large bullet. Without a heavy crimp my velocities spread out a good bit. Same as my 45-70, and 44 Magnum.

But when tried crimping on 223's and 30-06 I did not notice much difference at all.

So first I think it depends on your cartridge of choice. And second the size of those bullets, and then the rate of burn of your powder. I think slow burning powders definitely benefit from a crimp. Just be sure to be safe with pressures. Crimping is definitely going to cause a spkie.. But sometimes spikes are good for accurcy. Tom.