any difference in deflagration speed, efficiency, temperature, and gas output?
The propellant for my old howitzer was Ammonium Nitrate based, but lacking the blackpowder base ingredients.
However, the results from the swap of Ammonium Nitrate in place of Potassium Nitrate should give better powder performance, though with some extra heat.
Should get a yellow orange flame form a controlled burn of the stuff, and the smell should be similar to more modern powders.
Should also burn faster.
As for actual numbers, I don't have those in my head, but the performance should be better overall.