If the guy behind the trigger can put the animal down with 223 then why not? Who am I to tell them otherwise? If I was in the field with a 223 and an elk presented itself for I shot I wouldn't hesitate to put one through its neck. I'm willing to bet a shot behind the shoulder with a decent bullet would put them down in short order too.
There are videos on YouTube of guys culling redstags and rusa deer with 204's and 223's. Head and neck shots.
