A Shiloh Sharps 50-140 Express? I would run only the finest Swiss black powder down the barrel of that beauty. Order it from Track of the Wolf:
Swiss brand: "Imported in sporting grades Fg, FFg, FFFg, and the intermediate F-1/2g granulation for Sharps rifles."
http://www.trackofthewolf.com/List/Item.aspx/135/1