I am new to this site but have received a lot of great info. I have a 280 Ackley SAAMI chamber and using Nosler brass. I measured the head space of fired cases at 2.137, full length sized the fired cases and they measure the same 2.137. I was thinking the FL sized case would bump the shoulder back more than the fired case? The gunsmith who cut the barrel requested the dies and sized brass before chambering the barrel. Thanks in advance.