The .308 will serve you well, and there are a ton of good rounds to choose from- 150, 165, 168, 175, and 180 are all good choices. TSX, TMK, Partition, Accubond, Terminal Ascent, Trophy Bonded, Trophy Copper, will all get the job done at 300 yards. I shot my bull last fall through both lungs with the 175 TA at 80 yards. Caliber size entry hole and 3” exit after smashing a far rib.