I really enjoy shooting APP as well. It has that ‘self lubing’ quality that works great with coated bullets, keeps fouling to an absolute minimum and the cylinders spinning all day long. As Sedalia Dave mentioned, it’s a snap to clean and definitely produces a more smoke than an equal measure of BP
I don’t know for sure but it appears as if Black MZ and APP are one in the same or at least very similar. In fact, APP may have manufactured it for sale under the Alliant brand. I came across a patent number covering APP and also a reference that Black MZ was licensed/produced under the same number. Either way, APP is still available and fun to shoot.