RE: BC for the 277 cal bullet
And inside 300 yards, they don't make enough difference to matter with game the size of deer.
Just for s**ts and giggles I ran the numbers for the .308 cal 168gr Matchking (BC 0.462) vs the 165gr Hornady FB SP (BC 0.387) fired at 2900fps. At 300 yards the difference is less then 1/2" and only 5 fps. At 500 yards the difference is only 3.5" and 157 fps. So unless you plan to shoot at 500 yards or more, the difference doesn't matter.
I'd suggest that you buy the best hunting bullet for your chosen game animal, and don't worry about BC unless you shoot far enough for it to matter.
Mike