I think alot of folks dont adjust their full length dies properly. When done correctly there is usually very little sizing done to a fired case. Neck sizing or full length sizing both work fine as long as the loaded round is straight, and the bullet is sitting in the chamber square to the bore. If you have a full length die set to size more than needed for your chamber, then the bullet wont be square to the bore. And if you neck size with a die that pulls the neck out of concentricity the same thing happens. The issue isnt whether a case is full length or neck sized, but whether or not it is straight and a good fit in the chamber that it was loaded for. That can be done with either die, and it can be missed with either die too.