Are you saying that a bullet of .223 through the heart or lungs of a deer won't kill it? How dead is dead? I don't need to understand terminal ballistics (though I do) to realize that turning the heart to pulp, which the .223 can do, kills animals dead. To argue otherwise is silly. How many deer to you see running around w/o a heart? If you put the bullet where the bullet should go...regardless of what caliber you choose to use....you'll have a dead deer. Gutshoot it or take out a lower leg, and it doesn't matter what you are shooting, you have a wounded critter on your hands. Just like I wouldn't take a 100 yard shot with a bow or a 200 yard shot with a smoothbore 12 gauge, I certainly wouldn't take a 300 yard shot on a deer with a .223. Put that same deer (Nothern, Southern, Mulie, Whitetail, makes no difference) at 100 yards, and I'll kill it dead every time, if I wait for the right shot...which we all should do 100 % of the time anyway. If you are the sort of hunter who has no patience, who has to take a shot "right now" because "it may be the only chance I get".....the .223 probably isn't your ideal choice. I can openly admit that. I don't have such issues where I hunt, often seeing over 100 deer a day. If my goal is to simply kill deer, achieving it isn't much of a challenge, and that means, I can pick and choose my shots. If you can't, or aren't willing to, my personal opinion is that you shouldnt be hunting at all, but if you must, the .223 isn't the gun for you most likely