That's the same gun I shoot. Mine is nicknamed the Terminator, as it usually terminates my season early, and has accounted for a pile of whitetails. I put the tang-mounted T/C Peepsight on it, and bored out the aperture to the ID of the insert for hunting. It is a very accurate rifle. A soda can is not safe at 100 yds., and that's more than adequate for my hunting needs. I shoot 435 grain Maxiballs that I make with a T/C mould, over 100 gr. of Pyrodex. Since they are accurate, I haven't considered other bullets. With muzzleloaders, I like the biggest chunk of soft lead I can get to fly straight.

In theory at least, a shorter bullet of similar design should be better stabilized than a longer one with the 1/48 twist. BUT there are so many other variables that contribute to accuracy that it is hard to say which will be more accurate. Try them and compare.