Interestingly after I got my 300 WSM Frontier compact, I was told by a friend purely off the cuff which was a totally knee jerk reaction, that quoting him,,,,,"I basically got the equivalent of a 24" barreled 308.
A few weeks later with him as my witness using HIS chrony, I blew his assessment to Mars and beyond.
Well hardy har har,,,,,,,,,,
Couple a faster bore along with some RL17 (only), I believe it is possible for some 308s to maybe get 2750 to 2800 fps with a 180 gr bullet from a 20.5" barrel without pressure signs.
If Montana`s 308 can go 2700 fps using a 200 grainer, than 2750 to 2800 using a 180 is very feasible from HIS rifle.
