One of my good friends dosent like shooting Axis deer with anything less than his .300
Hes shot one since highschool, and is very comfortable with it.
At the same time we were shooting .223s a lot also. He had a mini-14, and I shot a 700 ADL. We shot a fair amount of 70gr speer semi spitzers, 64gr PPs, and a pile of 52-55gr varmint bullets, mostly 52gr AE hollow points. As far as I can remember we didn't lose any.
At this point I've got no issue with someone using a .223 for deer, as I've seen it work first hand on....a pile (I literally don't know how many head) of game. But I now prefer to shoot a heavier round, even for the relatively little critters we have here....I also have no great love for the .243, good round tho it is.
Also while I still take head shots, Im not a fan of front on, or side facing, especially with the .223 or other smaller rounds. Theres just too much real estate that you can hit, that wont cause immediate death. Again, don't have a negative opinion on other folks taking those shots, but I try to avoid them.....
IMO, you have to do what YOUR comfortable with.