Welcome to the forum. Frontier Gander can tell you all you need to know about that rifle. He is selling one, or just sold one. They are a good rifle. I am sure it will shoot well for you.. Give Frontier Gander an IM or start a new thread where he and others will see it. I am sure they will chip in with information for you.

Otherwise load 90-100 grains of Pyrodex RS (if a percussion cap model) or Goex 2f (if a flintlock) and a patched .530 roundball and let it go. Of course if you are real new to all of this, you might want to ask for some advise on how to get started with the rifle as well....