I really enjoy my GPR flintlock. Hopefully my shoulder will someday let me shoot it again.
You really need to get some real blackpowder though.
It's a difficult market to find much of anything right now. I've been trying to find some 2F Triple Seven to replace my rapidly diminishing supply of the one bottle I have right now.
Grafs appears to have Scheutzen 2F in stock, so I ordered 4 pounds from them this morning, along with another 200 balls and wads. Didn't have priming caps though.
So in a week or so I should be able to compare Triple Seven to "real black" and see what the fuss is all about.