You need to keep all .45 ACP cases (or any auto brass that headspaces on the mouth) as close to max. O/A length as you can, in order to make sure each round headspaces uniformly from shot to shot. Bell the case mouths the least amount you can get away with, and still be able to start the bullets into the case without crumpling the mouth. Once the bullet is seated, check to see if the rounds will drop into the pistol's chamber all the way. If they do, then you will not need to apply any crimp at all, not even a taper crimp. I check this by stripping my pistol, and using the barrel as a gauge. If you can get the rounds to work correctly with minimum belling andno crimping, 45 ACP brass will virtually last forever, as long as the case mouths aren't buggered up too much buy the pistol on ejection.

I am NOT familiar with the LEE "Factory Crimp" die for the.45 ACP, but I have NEVER SEEN any .45 ACP factory ammo that had any crimp at all, and the other Lee crimping dies I have seen all apply a roll-type crimp, which is not used on auto cartridges since it would ruin the headspacing edge you need on these cases.

I have never had to crimp any .45 ACP rounds I have loaded. They all worked just fine right out of the seating die, which DOES remove the bell as the bullet is being seated........