Sure a .223 will kill deer, but there are plenty of other calibers that will be more lethal and ethical. Unless your going for head shots I would get something bigger. The smallest I would recommend is a .243 even then that's a little small IMO. I have a 243 and a 30-06 but I always take the 30-06 because its more lethal and ethical. A 30-06 or .308 have just a tiny bit more recoil than a .243, and when you got buck fever in the woods you won't even feel it.