There's a fellow on youtube who loaded American Pioneer Powder 3F into the bore of his India made flintlock and using Goex 4F in the pan, he fired 10 shots without a misfire.
The caption for the video states: "Trying out some new powder, touted as a clean burning black powder substitute. I've read a huge difference of opinion about this powder, and several people flatly state that it will NOT work in a flintlock. Well, here you have it. I fired 10 shots of varying powder charge, all lead ball, and not one misfire or failure to discharge. I think the FFFg is the right choice, the grain size is bigger than regular black powder, so having the FFFg probably helped with ignition here. Also, prime the pan with NORMAL black powder, it's not a big deal and doesn't make a big mess.
Clean up was a breeze and nearly zero fouling. Very happy."
The next 9 second video was posted by the same fellow 2 days later.
The caption states: "This is I think the 8th shot out of the musket without swabbing, cleaning or lube of any kind.
After 15 shots the barrel still looked 'brand new', this powder seems consistent and reliable, not a single misfire that day.
....also at 20 paces we hit the crock-pot every time.. .71 lead ball with paper cartridge wadding."