I get asked sometimes (actually never) “should I crimp my ammo or not?”
That’s a complicated question. To crimp ammo is to simply apply pressure around the case mouth and squeeze the case against the bullet jacket. Some reloaders say it helps accuracy, and some say it deteriorates accuracy. The theory is that crimping ensures uniform neck tension with each crimp being the same from bullet to bullet. So did it make a difference?
All I can do is share my results so you can come to your own conclusion.
Using my go to accuracy testing load, Hornady 53 ELD match, and a Lee Factory Crimp Die… I loaded and crimped ten ELDs and then left ten un-crimped.
As we can see, there are definitely more flyers in the crimped ammo. The group is far more spread out and the mean radius expanded from .36 MOA to .58 MOA.
The crimp on my Lee is set very light. I don’t have a good measure of how much crimp is present, but the wings of the LEE FCD just kiss the cartridge. Even with such a “small” crimp, the group size opened up substantially.
Take it for what its worth, but if you found any interesting factoids about crimping that you have personally observed, sound off below!