Now, if we had some dowels, and some sort of apparatus that could ... Oh, nevermind...

The largest critters I've killed with a .223 are coyotes, generally KO'd instantly with a well-placed heart/lung shot, almost never anchored immediately with poorer placement. On the other hand, I've shot or seen coyotes shot with .308, 7MM Mag, and etc., that were demolished, in some cases appearing more likely dynamited than shot. (Ruins the pelts, by the way...) I think by most measures, there's little question that at any range, the .308's terminal ballistics are superior to the .223, but that the .223/5.56MM is capable of adequate injury to put homo sapiens out of the fight, if not permanently. That acquiesed, the question is appropriately not of caliber but of weapons platform, and here the .223 wins on several counts --- weight (of both rifle and ammo), recoil, recoil recovery speed, reduced potential of collateral damage, etc. If the targets are at reasonable self-defense/law-enforcement ranges, seems to me the .223 is up to the task. If long-range sniping is the order of the day, give me a thirty-something.