Victorcharlie: When I was growing up in Tennessee the minimum caliber you could use for hunting big game, Deer, Bear, and Boar, was .25 caliber. Knew lots of people that thought a .243 was good but the state said no. Anyway was home on leave one year, from Alaska. My Mom's church choir leader came over to meet me and visit. Something about this guy just did not hit me right, I took a dislike to him from the very first. I had my Parker-Haile in .308 with me and was showing it to Dad and my Uncle. This guy said "Man that's way too much gun for whitetail, kicks too hard". Then he asked what he could do to stop his bullets from going all the way through whitetails, would a hollow point work better? He had lost three deer so far that year, bullets were going right through them with out killing them. They were running off and he could not find them. I asked what caliber and bullet he was using. He said "I am shooting an 80gr jacketed bullet out of a Remington model seven in .243". I looked him in the eye and replied, "First thing you need to do is get a real deer gun, one that's legal". I handed him a copy of the regs and pointed out the reference to minimum caliber for Deer, being .25. This guy come unglued, he went to spluttering, every time he went to say something he got so flustered he could not speak. He kept slapping the page in the reg book with the back of his hand. He must have paced back and forth across my Dad's den ten times. Kept turning around and slapping that book. Finally he stormed out the door without finishing a single sentence he had started. Jumped into his pickup and threw gravel all the way to the street. My Dad and Uncle got to laughing so hard they were crying. My Uncle said "It sounds like he needs to learn how to shoot". Dad agreed.
Never saw that man again. He refused to come to Mom and Dad's house if he thought I was there. Dad told me he quite hunting deer for many years after that. Mom thinks I am the meanest man alive.
Oh I know a .243 will kill deer with no problems if you do your part. I've killed many Caribou with one.