US Military issued paper-wrapped cartridge:
Ball - .530 diameter, powder charge = 35 grains of rifle powder. The powder charge was used for flint and percussion pistols. When used with the flint pistol, priming was done using the powder in the cartridge. Use 5 grains, don't completely fill the pan.
In standard military practice for all arms loaded with cartridges, the cartridge paper was torn at the back, the priming powder was placed in the pan and the frizzen closed. The remainder of the powder was poured down the barrel and the ball, still encased in the cartridge paper, was rammed home.
Since it is unlikely that you will be using cartridges, load first with 30 grains of fffg powder, ram ball home with paper wadding on top to keep the loose ball from rolling out the muzzle, and prime.