Actually 60% of ARs are used for two forms of hunting: predator control and varmint hunting. The .223 (5.56mm) round is pathetically weak. The ONLY thing that makes it effective for the Army is the select fire BURST mode. You NEED 3-4 fast hits to disable an enemy soldier with one. An old M-14 with the .308 Winchester (7.62NATO) is a big game round. In 'Nam before the M-16 was adopted the M-14 was a brush buster.
We also have the National Matches ALL shot with M-1 (WW2) or M1-A rifles (Korea) and the Three Gun matches where you need a tactical carbine, tactical shotgun and pistol. Tens of thousands compete including ladies.