A 223 with a good bullet (Barnes, Nosler Partition, PowerPoint, Trophy Bonded Bear Claw, etc.) will do a fine job on deer...I have taken them with clean, 1 shot kills with far weaker rounds.
The reason most people say the 223 is not good for deer is because up until a few years ago...there were no bullets that would stay together long enough to penetrate deep enough...we don't have that problem anymore....the 223 is plenty powerful for deer, they are not hard to kill. I filled my freezer last year with a 45 acp (my Stinger).
Pick your shots...broadside, aim for the lungs or liver.
Facing you...straight through the neck or just above the middle of the chest.
Here is a pic of a Barnes bullet, 62 grain TSX boattail...it hit hard packed slate rock at 2900 fps and penetrated plenty far enough (the 243 didn't do much better with the same type bullet)...and its still in 1 piece except for the petals, which do not come off in flesh.
The range should be kept to 100 yards...but never more than 150 yards. The 223 is capable of doing its job for quite a ways farther than 150 yards....but the man holding the gun should always have "ethics" and "his own limitations" in mind.
There is nothing better than a good caliber debate:wink: