To hookeye's point - long (heavy) bullets do start to eat up case capacity. But it all depends what you want to do. I did load work up for a guy wanting to shoot 220's in a 308 several years ago for black bear. These were painfully slow and the trajectory reflected it, BUT, despite it's low velocity (would have to pull out the book to remember), I do recall there was still considerably greater momentum on the bullet at range than what I had on the 180grn load I had recommended to him. Momentum = penetration, so it had the advantage at long range, despite the trajectory.
I tend to recommend 165/168 or 180grn bullets for the 308win, across the board. 150's are fine, but at the lighter end of the spectrum for me. I shot 130-150 in 308win for many years, so maybe it's just age catching up with me, but I have seen enough to realize now I would much rather have a heavier for caliber, heavier for cartridge bullet than a light one --> WITHIN REASON! I'm not gonna start loading 200-220's in 308win any time soon.