There is many the deer that has died to the .223. I guess they are all going to have to come back to life since they were killed with an unethical caliber, and every body needs to go and buy a howitzer to make sure that the deer is killed as quickly as possible. I have used a .270 and a .30-30 all my life for deer but would not hesitate to grab a .223 for deer hunting. My sister killed one last year with it in its bed. Shot it right under the ear never moved. Shot placement is the key and a good bullet helps. And I can personally say that if it can kill a 150 pound hog it will kill a 200 pound deer no problem. We use AR-15s for hogs all the time and they do the job just fine.