It might work, for a few shots. A rifled musket like that needs a soft lube to keep the powder fouling soft. BP fouling will build up and dry into a hard fouling that makes seating the mini hard and it also can be hard on accuracy. Beeswax and crisco always worked well for me in those guns. It is messy as all get out but it sure shot well.
Save the coating stuff for smokeless powder, you will be much happier that way.