I'd feel pretty confident shooting a deer at point blank range with a 22 that had a muzzle velocity with a 62 gr. TSX of 1900fps or 75 gr. Scirocco at 2100 fps, the speed either fired from a 223 will be at 400 yards. Of course you can add a couple hundred fps to those 400 yard impact velocities via bigger cased .224's.
But I get the gist of using more rifle for big bodied/open country type hunting.