Sure the 223 can do the trick, BUT it's lackluster penetration limits your shot angles, flush broadside quartering away, or neckshots are highly recommended when you are only talking 12-15" of punch. A bullet through the vitals kills period, but getting through the vitals on a raking shot requires a bit more. I am sure hunting with an AR is fun but me personally I am sticking with my 6.5x55, 30-06, 7mm-08, 7mm Rem Mag, 270 WSM and 308, all of which can easily get through the vitals at any angle I care to shoot.