The Belgian caplock used loose black powder & ball. The barrels thus far have not come free in spite of being soaked for weeks in Kroil.
I admit however, that I have not tried very hard to remove them, assuming 100+ years of blackpowder fouling and mercuric percussion caps causing corrosion is holding them in place.
Trigger control + Breath control + Sight alignment = Gun Control.
NRA Smallbore Prone Master