I grew up around .243 bashers, and became one myself. For some odd reason, my Dad, who was an ardent basher, bought a .243 and strated killing deer with it (he was flinching with bigger cals) I started re thinking things.
Dads .243 came to me on his passing, and both bamaboy and myself had shot deer with it. We initially used 100 gr Corelokts, and now reload 100 gr partitions.
The only people who can't kill deer cleanly with a .243 are those that haven't tried. Just watch your bullet choice