My own personal flintlock rifle is a 62 cal. I have used it for 21 years now and I have enjoyed many hunts with it.
62 seems a bit bigger than is needed fort deer and antelope, but so what?
It works!
It's very good on elk, and the one moose I killed with it dropped on his chest when the ball broke his front upper legs bones. It was dramatic.
My load is 140 gr of 3F Goex and a .600 ball cast from wheel weight metal, air cooled.