I agree with those who say the .223 is not a deer caliber! Any shot that is less than perfect will be a lost deer. I consider the .243/6MM to be the minimum for deer. The .243 is light on the shoulder and will handle any whitetail around! If you can handle more gun, then go for something like a 7MM/08 or larger, there is no such thing as overkill! It just can't be "too dead!"
But with the .223 class calibers there is such a thing as "not dead enough!" With the good low recoil, hard hitters on the market today, there is just no good reason to use a varmint gun on deer. It is just plain inhumane!