According to the Davide Pedersolli sight, your Kentucky rifle has a 1-47 twist. I think the metric aspect of them causes the sight difference from the standard 1-48. So the rifle should be able to shoot a lot of different projectiles very well. For starters and fun, try some .490 roundball in a .018 patch with about 70-90 grains of Pyrodex RS under them. It might surprise you how accurate it is.

I would forget the minnie balls. In that twist I think you will be disappointed. I have a LEE mold for them though. I never use it since I can not find a rifle of mine that will shoot them accurate. I also have a minnie mold in .54 caliber as well. Maxiball might shoot well for you. The Lyman Maxiball is 370 grains. It is also flat bottom. I would start shooting them with 70 grains of powder. You might want to try a wad as well. Then work the powder charge up until the accuracy either improves or gets worse. I would not go over 100 grains of powder with them, but that is plenty of horse power.

You could try some sabots. 300 grain Hornady XTP's with about 90 grains of powder. Whether it will work is up to your rifle. Also the suggest of the REAL conicals is a good one. I shoot them in 1-48 twist and they are deer killers. Also since you cast them from a LEE mold, they are cheap to cast and easy to shoot.

It is very hard for any of use to tell you.. yes, this load will be accurate. That's because I have similar make rifles, and they do not shoot the same things. They are close mind you, but not the same. So all you can do is get a lot of different projectiles and start putting in some range time. I would start with the roundball and the maxiball. Limit your shooting range to 100 yards and you should be fine.

That is sure a pretty rifle you have. I bet it will be a good shooter. Keep us posted please...