I would not recommend a .223 for deer. Those light bullets going around 3000 FPS just kinda blow up before they get the penetration needed, especially if the bullet strikes a shoulder.
it is just too likely that you will end up with a wounded deer.
Of course, if you are good enough to put that little pill in the brain, you have your deer, guaranteed. If you hunt deer with a .223, just disipline yourself to shoot the brain. Its no big deal, a deers head is as big a target as a jackrabit, and many a jack has been dispatched with a .223. Past 250 yards those little slugs drop off pretty fast too, so no 500 yard shots. OK?
I have a 222 Rem, which is very similar, and have killed deer with it. Twice I took body shots. One I hit the backbone about midships. That slowed the deer down since the back legs were out of commission. The other one was a little too long of shot maybe 250 yards, and I am sure I made a good hit aiming for the heart, but that one ran away. I tracked it till dark, but never caught up. After that I would only shoot at the head, with that little cartridge. I kinda lost count, but must have killed over a dozen deer with head shots using the 222 Rem. Then I got a 270.
Now I can shoot deer over 250 yards away.
Any deer standing still up to 200 yards is an easy kill with a head shot, with the 22 cal, and hitting something that large is no big shakes with a varmit rifle. Another plus, you have a nice clean carcas. No stinkin gut shot mess and no ruined meat.
I started out telling you I don't recommend the .223, now i'm telling you this????? Not sure if I'm talking you out of it or in to it.
It must be gettin late?
Get a .270 for deer! Hey the 270 makes good head kills too.

It will mess up your antlers though, so maybe its best to hit the spot where the head hooks onto the neck? Bust that spinal cord and the deer is yours too. What, you don't want to mess up the cape? OK, so take a heart shot with a 270 or 30-06!
Have a great hunt.