this may be to much for the average reloader,,but when I had a VSSF 308,I had a lot of time on my hands then,,this is the experiment I did,,if I remember correct,,
I removed the expander plug from the fl size die,,and sized a case,,I measured the inside of the neck and got something like .302,,,what I did was turned the necks down from .018 to .013,,then I sized one of those cases and measured the inside of the neck and got .307..after all that I put the expander plug back in and when I sized the cases you could just barely feel the expander pull back through the neck,,
instead of getting a bushing die to fit the brass I turned the brass to fit the die,,,it worked in that rifle so well that I shot the same 200 cases 20 times ,,190 Berger VLD and IMR 4350 would shoot lights out