Pyrodex is not 777! :hmm:
Pyrodex does work, after a fashion, but 777? :idunno:
And, I have been unable to get anything approaching acceptable results using anything but BP as a prime. Even in the Firestorm and therein lies the issue. If you need BP for prime why not use it as the main load?
IMHO, I see none of the subs offering any clear advantage over Pyrodex for side lock shooters. Cap locks included.