I tried nitrating paper for cartridges using stump remover which was mostly potassium nitrate but the brand I got contained some kind of waxy scum that was almost impossible to remove and left the paper contaminated so much that glue would not stick. I used the rest of the stump remover as fertilizer and went another route.
I had the gun, a Pedersoli percussion Sharps, modified by Hahn Machine Works, and started using Hahn tubes and the paper cartridge problem was solved.
Perhaps not precisely period correct, but I have shot 30 rounds without cleaning or stopping to fiddle with the breech block and I prefer reliability to period correct any day.
Yr’ Obt’ Svt’