[Unclenick]

Did you have fun getting the loose powder out of the action?

Check first with a case gauge to see if the extracted case is now shorter at the shoulder than your new loads. If it is, it sized in the chamber enough that the neck may have flowed forward. If so, you want to know if the bullet went far enough forward to touch the lands because of the neck elongating or because the bullet actually got loose. If it's the former, you want to trim your necks a little shorter so the crimp cannelure is lined up with the case mouth at a shorter seating depth. Military minimum case length is 2.000". SAAMI is 1.995". Aim at the military number and don't fret a thousandth or two under if it happens.

The next question I have is about the crimp. A crimp can sometimes actually loosen a bullet by pressing the case mouth and bullet down hard enough to bulge the sides of the neck beneath it away from the bullet. I never crimp my AR ammo and have never had a problem with it. You might try some not crimped. I assume you don't have a bullet pulling gauge for this activity, but you might be able to tell with a chronograph. If you can shoot some crimped and uncrimped rounds side by side (alternate them to compensate for fouling and barrel heating) and detect any increase in the average velocity for the uncrimped ammo, then you are likely loosening rather than tightening the case grip on the bullets.