I have to agree that Power Pistol is one of the beeter (maybe even better) powders to produce flash. A safe but max load of Power Pistol in almost any pistol cartridge will produce a hansome flame that is visible at noon on a brightly lit day.
The bad side is, you can't hit beans. The good side is you won't care because the flameout will certainly make you grin from ear to ear. Accuracy is over rated anyway. The good side is you will definitely impress every onlooker with your flashiness.
The bad side. If you get in a gunfight in the dark, you will be night blind for 2-4 seconds after each shot. The good side is the perp will also be night blind.