Let me start by saying there are far many better choices for deer hunting. With that also being said I know first hand the devastation the 223 can do to a deer. Would I recommend it to anyone? No way. I myself have probably taken 20+ deer with a 223 and also the 222 and have never had any bad things happen. I’ve also shot premium bonded bullets or the Barnes all copper type bullets in the 60-70grain range 55ish for the 222). I also kept my shots to 75 yards and closer and took high probability shots (neck, chest) at unalarmed deer. If they didn’t fall they never made it past 30-40 yards. If the shot wasn’t perfect I never took it. In the right hands of a patient hunter they’re adequate but again, I wouldn’t recommend it to anyone.