I'm no bench rest shooter, but I do read alot and try to make good loads. If I want the most uniform loads possible, I will fl size a new case. The likelyhood that they are deformed is not very good, but I use Winchester, Remington or whatever else the local shop has, and their quality is lower than Norma.
As far as setting dies, I recomend putting pressure against the die w/ the ram before and while you tighten the collet on all your dies (trues the die to the press and reduces runout). For the seater die, I use a machined washer that is true to do this because you don't want to set the seater die to touch the ram. I also use a bushing to give me the most consistent seating depth ( I took a washer that the cartidge fit inside of and filed it down to true it up).
I a about to try to use some cases that I neck sized w/out a ball expander because I've read that the expander ball is the number one cause for bullet runout.
I don't know much, but I'm happy to share my ignorance! /ubbthreads/images/graemlins/cool.gif