We’ve been over this many times. There is no magic and if you start out with what follows, it will save a lot of time, money and frustration.
First off. KNOW your ACTUAL bore size and that means measure it. Do not make the mistake of assuming Luigi got the bore size right. I’ve seen bores go from .574 all the way to .585. You will want to order or cast minies .001 under bore size for best results.
Second. With that known, contact Lodgewood for a sampler of correct size minies. There is NO commercial source other than Lodgewood for this. Not Track, not Log Cabin, not October Country, in short, you want to get proper minies that are cast and sized correctly. Lodgewood specializes in military arms, the rest do not and the guy casting for them is a N-SSA competition shooter who knows his business.. With a known good size and style, then it’s time to order a mold.
Third. Use real black powder. Swiss is best. 2f or 3f, they’ll both work but you’ll find one has better accuracy and less fouling. Experimentation will tell. Use RWS or Scheutzen caps. CCI May work but they’re designed for reenactor blanks. Don’t get hung up on the historical service charge. Best accuracy will most likely happen from 40-50g 3f.
Fourth. Lube. Beeswax/(lard,crisco,tallow) Bore Butter is a short path to frustration. Melt the lube in a pan and dip the rings only. Filling the base will cause flyers. No serious competition shooter I know who wins will ever fill the base.
These guns shoot high with issue sights if you try to apply modern sight picture. The soldier was trained (sometimes) to aim center mass so a hit high is still a bad day on the receiving end.