In an old Lyman reloading handbook I have I found a suggested load for a NAVY KENTUCKY PISTOL 44 cal. .424 round ball, use .013 patch, 40.0 grs. FFFG black powder, no. 11 caps for percussion pistols. For flint pistols, fill the pan with FFFFG or FFFG black powder.
Hope this helps, be careful.