I am trying to spec out a flintlock longrifle for my grandfather. He wants one that is (60"-72") with a rifle twist of 1-66 to 1-72. I have narrowed down two barrels both are Rice one is 46" and goes up to. 62 cal and the other is 48" and goes up to .58. He is 67 years old and he loves the old guns like he used to see people use when he was kid going hunting i.e. long flintlock. I live in Maryland and the gun will only be used for hunting white tail deer. I'm trying to choose between .54, .58 and .62 cal everyone here knows how these various calibers perform better than I do so any input is helpful.