patchholder, I use APP and if you keep it dehumidified it gives the same velocity for the same load but if you let it gather any moisture at all it gets irregular,and shoots all over the place. I have experimented with APP and suspect that the other subs with the same base will have the same problem; since I dont care much for "crudring even though I finally solved that problem I think good old moisture resistant Pyrodex may very well be the best answer and if you pick up a dozen cans at 6 bucks a can at the end of the year sale at walmart like I did its cheap to.
Lee