Home Forums Reloading Big Game Rifles Lee Factory Crimp Die

Has anyone here or are there outside sources that have proved out Lee's theory?

Lee's theory:

"Tests demonstrate that even bullets with no cannelure will shoot more accurately if crimped in place with the Lee Factory Crimp Die. A firm crimp improves accuracy because pressure must build to a higher level before the bullet begins to move. This higher start pressure insures a more uniform pressure curve and less velocity variation. Even powder selection is less critical. Until now, handloaders seated the bullet to touch the rifling to achieve similar results. This is not always possible nor desirable."

Some people are just never going to be convinced of anything unless they do their self and half of those can't even convince their self of what they already know.

Just buy ONE for your self tighta** and try it.

I'll take this as NO, you have not tried it.

Didn't do anything for me and if you over do it you will get wonky case necks. But it has worked for others so I can't make any hard and fast claim.

Why do you want to crimp? If for a hard kicker or auto maybe yes but for anything else adjusting neck tension is better and I would invest in a collet die before getting a crimp die if accuracy is the objective. Lots written on how to tweak them for best work.

Whether the claim is accurate or not is not for me to say, but have played a lot with varying neck tension which in my book is kinda like crimping, depending on your definition of crimping. Some things make great changes, and others not so great. Always found that 2-4 thou tension is adequate under most circumstances. Anyway a guy over on accurate shooter did a small sample test matching your question. Take the data for what it’s worth. I didn’t see any drastic enough change to brag about.

http://www.accuratereloading.com/crimping.html

Mine reside in the junk box

I use 'em for every caliber I load for. 44, 357, 9mm, 30-06, 45-70, 223, 10mm...

Now, do you know any more than you did when you started the thread? Some people like 'em, some people hate 'em. You don't know any of those guys, so who are you going to believe?

I'm in the "some people hate 'em" camp.

If you make straight ammo with proper neck tension, they are not going to help you.

If the LFCD makes you ammo shoot better, go back and address the other two variables.

I use them on all straight wall cartridges, it’s just easier and more forgiving if your cases are not all trimmed perfectly. 44,454, 357,45-70, etc

I also crimp every semi-auto rifle load with one, because a setback bullet can ruin your day. As far as accuracy, I noticed no difference in my bolt rifles so I don’t use them for those rounds, but it didn’t seem to hurt either.

I know most people don’t crimp rifle rounds, but I’ve had .223 bullets get set back because they didn’t feed properly out of the mag in an AR so I’m probably over anal about it. I know plenty of folks that don’t and get along fine.

I've tested otherwise identical loads in bottle neck cartridges that were crimped with the Lee die and uncrimped using bullets with a crimping groove and the bullets seated to use this groove. The result has been the same the three or four times I did it: The crimped loads shot slightly worse. I use it when I have to crimp such as a .30-30, but not otherwise.

Consistent neck tension is key to accuracy. If you don't know how to accomplish this through annealing and proper sizing, the Lee FCD may be a shortcut for you. I never could accomplish with it what Lee stated. I had better results annealing cases.

I use them for 223’s I shoot in AR’s also.

I use them to put a crimp on cannelured bullets mostly. A second die for crimping comes in handy and the LFC die performs that task.

You have to work up loads using a crimp die because it does change pressure. If you try and use the crimp die with an already developed load, then accuracy is out the window.

I saw an accuracy increase when using the factory crimp die with the 22 Hornet and K Hornet, otherwise used them on 30/30, 35 Rem, and 444 Marlin.

Swifty, thanks for posting info.

In the context of my question, did you test for accuracy on crimped versus non-crimped?

I did.
That’s why there in the junk box

I use them for 5.56, my M1 Garand ammo, and my Rem 350 mag. I have no idea which works best, crimped or not.

Didn't need to.

I shot and reloaded all those same ammunition for decades before I ever first tried a Lee FC die.

I didn't buy the next one because the first one was worse.