Yes, you can kill deer with a 223 Rem. ... and a 222 Rem. ... and a 22 Swift .... and a 22 Mag. ... and a 22 LR ... but why chose such a marginal round when a 243 Win. , 260 Rem., 6mm Rem., or 6.5x55 SE (which are all relatively light recoil rounds) will do a much better job. And as mentioned, 22 cal. not legal.