What you'll probably end up doing is getting some black powder and then loading a portion of your gun's powder charge with the black and finishing with the Pyrodex. As a guess, if you want a 75 grain powder charge, pour in 25 grains of black powder first, so that will be near the touch hole, then pour in another 50 grains of Pyrodex. That will give you prompt ignition. As an example, even the Pyrodex pellets have black powder on one end to aid ignition. In the end, after you have used up your can of Pyrodex with the duplex loadings, you won't buy any more.