Put a 243 in the engine room of a white tail and its not going anyplace.
My six year old son got his first buck with a Savage 243 bolt action at 350 yrds with a 70 grain bullet. Ive take countless with it one at 600 yards. None went more than 10 yards before dropping and most fell in their tracks.
I did find heavier grain deer loads dont do as well as the lighter grain.
For a first deer rifle for a kid or for an old deer hunter you cant go wrong with it.
Gut shoot a buck with a 243 or a cannon and youll likely track it for a good good while.