If you're not getting enough neck tension because of repeated firings, you can try annealing them- I found that its much more effort than what its worth especially when most flavors of brass are readily available.

The only crimps I use are for autoloaders- for the pistols I shot, a slight taper crimp is necessary to get them to chamber reliably- I just make up a dummy round with the case mouth at the correctly spec'd diameter and bullet seating depth to set up my seating dies.

For loading for my M1- I've gone both ways, but seeing that the bolt closes with alot of force, I've decided to put a very slight crimp on the case- I screw the dies down until it meets resistance with the case, then screw it down another 1/4 turn. The amount of crimp is very slight so as to not deforem the case or bullet, but enough to give an extra bit of neck tension.

I've used the Lee Factory crimp die for 8x57 and .308 and have gotten slightly better accuracy with each using it.