One thing that I havent seen mentioned in this thread is the need for full length resizing for a semi automatic rifle.

Neck sizers are fine for bolt actions that have the camming action to help them fit in the chamber, but if you are using a semi auto like a Remington 7400 or a Browning BAR, if the cases arent full length resized then they arent going to chamber at all.

Its true that a fired case that expands to the same dimensions as the chamber will be more accurate than one that must expand to the chamber but this only works for the bolt actions.

My 7400 30-06 wont even think about chambering a round unless its been full length resized. For my bolt actions, I can get away with neck sizing only and it works well.