What to put on variation form?

[tacfoley]

You'll need an explosive licence to buy the Blackpowder unless you use one of the substitutes.

Correct, as well as an approved safety container.

With regard to subs, remember that any of the subs are generally MORE corrosive than basic BP. Clean the pistol as soon as possible after shooting - best on the bench as you stop shooting for the day. Babywipes are a good idea - use them after every cylinder-load to keep most of the glurn off. If you have access to denatured alcohol or cheap vodka, use it to swab out the barrel every couple of dozen shots, too.

Subs are also more energetic than an equal volume of the same grade of BP - that Pyrodex P [for pistol] loads less than an equal volume of black powder, and Triple 7 even less. That is to say, a 30gr load of 3Fg BP = 27gr of Pyrodex P and 25gr of Triple 7. YMMV. Both Pyrodex P and Triple 7 are about the same physical granulation as 3Fg BP. Pyrodex smells a little like BP, but Triple 7 smells like a fire at a beet processing facility.

In any case, unless the OP is going to shoot something really strange, the projectile IS an ordinary bullet - ball or conical. What is is NOT is a metallic cartridge of any kind. As he gets into shooting his new pistol, he might give some consideration to making paper cartridges using cigarette papers - much like the originals did back in the day. Instructions on how to do it from Baláscz Németh on Youtube - capandball - and others.

tac