I have a first generation Parker Hale Volunteer .451, but Rigby style rifling. You will need a platinum lined nipple as the ordinary musket nipples will cut out in 20 or 30 shots and blow your group. I have been shooting pure lead but after receiving some great information from a long range shooter with lots of supporting evidence, will be going to a lead tin alloy bullet when I get the opportunity. I load powder and wads, then with a damp patch wipe the barrel followed by a dry patch. If you do it with a completely empty barrel you will push crud into the patent breach and have all sorts of trouble getting the charge to go off.
The supporting evidence showed that pure lead bullets slumped badly in the barrel and lost a lot of their aerodynamic shape, hence going to a harder bullet. 1/30 lead tin so its not super hard. I use a charge of 85 grains of FFg Goex
.