Which is best? Best for what projectile? assuming since this is the Traditional part of the forum that you mean Patched round balls. It was found by Lyman nearly 30 years ago, that the bigger the ball the further down range it carries it's energy. As I recall a 75 caliber ball, retained nearly 75 of its energy at 100 yds, whereas the 50 cal lost about 55% of it's initial energy at 100 yds. A 75 caliber presents it's own difficulties, for hunting, and a rifle capable of accuracy would require some heavy barrel wall thickness and would be accordingly quite cumbersome. For that reason a 75 cal is fairly impractical. However, 62 caliber guns are out there and there are lots of 58 calibers guns. Many places that sell muzzleloader supplies will have 570 balls in stock. I'd vote for the 58 caliber. Back around 1982, CVA sold a big bore mountain rifle in 58 caliber. It was probably one of the best production guns in 58 caliber for hunting. As I recall, the renegade was also available in 58 for a year or two. I have a repro Civil War Zouave, that is pretty accurate in 58 and it can handle PRBs and minnie balls. Although the PRBs seem quite a bit more accurate.