58-cal is an easy choice for me. With 280 gr. roundball & regular lubed cotton patch or my custom Permatex Hand Cleaner-lubed patcharound .015-018 thick, that hunk of lead serves as a conical with mouth-dropping accuracy out-to 125 yards using only 70-75 gr. 777 FFF.
A nice 2nd choice is actually a regular conical with that caliber. Another outstanding accuracy report can be yours using the same 70-75 grains with either Buffalo Ballet conicals for that caliber. I prefer the 405 gr. Hollow Point Ballet myself. You can buy these bullets at
http://www.thunder-ridge-muzzleloading.com/buffalo.htm#ballet
Also for sale is the entire thunder-ridge onlinebusiness.... lol