RE: FACT OR FICTION?????
Fact.
With Pyrodex, it seemed to take forever to clean my gun and it was never truly clean. 777, now I run about 6 water-wet patches down the barrel, two dry ones, a lightly oiled one, clean the breech plug, and I'm DONE.
777 is also less corrosive (not it is NOT non-corrosive).
777 is much cheaper than Blackhorn, but if you do not shoot a lot it may be reasonable. Me, I shoot too much.