I've been reloading straight walled handgun rounds in a single stage press for a couple of years now. And am just getting into bottleneck rifles, 308. The first rounds I reloaded I fully resized with a coal of 2.805. They shot ok both from my 700 sps tac and my buddy's RR AR10. Getting more into it, one of the things I read, was to create a template round, blank with a seated bulled just shy of touching the barrel, for reference. I did this with fireformed brass from my factory rounds and Hornady bullets JHPBT 168 and 178 grains. With the 168 grains I got a coal of 2.8095. With the 178 grains I got 1.743 before the bullet didn't caught the barrel. And even with my limited experience from relaoding bottlenecks I find this difference extreme. Before settling on this coal I narrowed the range down with new bullets and case just in case the old ones got deformed by chambering. However they would chamber without effort in every case from 2.810 and down. The question is, how much attention should I pay to this? Stuipidly enough I didn't measure the coal on the factory rounds. My rifle seemed to like them - bunch of 3 shot groups at touchingf at 160 yds.