For years I have been squadded with the Nation’s best at Camp Perry. I also shot with National Champions, was squadded with one Saturday.
No one, and I mean no one, crimps match bullets. Not for AR’s, not for bolt rifles. Maybe black powder. But I am not loading black powder in my gas guns.
If there was one itsy bitsy teeny weeny accuracy advantage to crimping, everyone would do it.
The military crimps their bullets because some fully automatic mechanisms feed so fast that the bullet could become dislodged during chambering. This is not an issue with any semi auto matic mechanism I own. The military also used tar sealant if you want to go hardcore GI, and don’t forget to crimp the primer pocket.
Today’s match bullets are the best that have ever been. It boggles my mind to think that anyone thinks they can improve the concentricity of a match bullet by swaging it in the middle.
There is spring back to the bullet jackets, but I will bet that crimping permanently deforms the lead core. Why change the center of gravity by crimping?
Crimp for lever action guns fed through the tube, Vulcan type rotary cannons, maybe for elephant guns. Don’t crimp for AR’s. Use neck tension.
6.5 SMK grossly deformed by Lee Factory crimp die.
Here are some more problems with crimping. Shoulder collapsing.
I stole these pictures from a post from Walkalong.
http://www.thehighroad.org/showthread.php?t=595815
Too much roll crimp and the shoulder is deformed. This would cause a fail to chamber.