Pyrodex can be used pretty much interchangeably with black powder. It is apparently a more modern "smokeless?" propellant, mixed with a filler so that a given quantity, by volume - as black powder is usually measured in field use, gives about the same propellant energy as would be obtained with black powder. It can be used in muzzle loaders, flintlocks or cap and ball, or in cartridge loads for guns designed in the black powder era.

It is formulated to be "pressure regressive" like black powder - above a certain pressure the rate of burning of black powder tends to slow down. Most smokeless powders actually increase the rate of burning with increasing pressure, at least up to a point, - and a small error in quantity could easily blow your gun apart. Smokeless powder generally must be accurately weighed - you don't just pour a jigger down the muzzle.

Reenactment people probably prefer to use the "real" black powder, for the sake of authenticity. It does make somewhat more impressive smoke.

Both are used in "blackpowder" or "muzzleloading" hunting seasons, where states designate them. Both are also used in "blackpowder" target shooting.

Unless the situation has changed recently, there is no US manufacturer of "real" black powder now, and Pyrodex is safer and easier to ship and store.

Re: "steenkin bodges" - its from Treasure of the Sierra Madres" - Bogart; stolen, mangled, and used in Blazing Saddles and elsewhere. See Cowboy Lines for a recent debate.

John