Originally Posted by
cbrick
Here's an accuracy tip, I do this on my long range match loads. Neck size only. Lay a fired case on it's side and place a bullet next to it to where the case mouth lines up with the crimp groove, measure how far down the case the bullet seats and size only this much of the case. It will give your straight wall case a slight hour glass shape, how much so depends on how loose your chambers are. Most chambers are loose enough that the loaded round will lay at an angle meaning the center line of the bullet is not in line with the center line of the throat/bore. Sizing this way you take up some of the slop in the chamber and keep the bullet in better alignment before firing.
Rick