Even a .22lr can and has killed deer. Any doubt of that, check with your DNR. It is a common poacher's weapon. Sound doesn't carry as far. I personally have never used the .223, but my cousin has taken quite a few deer with both a .222 and a .223. I have no doubt it is effective.
You could not use it here, legally, but it would get the job done.
Shot placement matters more than bullet used.

An unemployed Jester, is nobody's Fool.

the only real difference between a good tracker and a bad tracker, is observation. all the same data is present for both. The rest, is understanding what you're seeing.

~Molɔ̀ːn Labé Skýla~