The first sub I ever tried was T7 out of a CVA Optima Pro. And it worked quite well. I've since stopped using T7. I do use Pyrodex RS and P out of my sidelock percussion rifles if it shoots well. Out of my flinters I only shoot BP, either FFg or FFFg again whatever shoots the best with a particular bullet. But honestly I have never had a ML the hasn't shot BP well - inline or sidelock. And I don't really see any advantage with the subs over BP with the exception of possibly Blackhorn 209. And then only for inlines.