If the only rifle you have is a .223 then I would say load it with 60 or 80 grain bullets and maybe you'll be good if you can place the shot.
But if your like most hunters that's probably your varmit rifle or your souped up semi auto AR or MINI 14 and just wanting to say "yeah well this gun killed this deer". Can it kill a deer? Of course. Head shots with anything down to a pellet rifle can kill a deer if placement is right and distance is right. Is it an ethical weapon? No. While the speed is there the mass just is not. Use something else. Good luck.