Great post brushhippie, very informative.
Rachen - is the sulfurless recipe measurements by volume or weight?
By volume. All my powder measures and spouts that I use to calculate materials are volumetric.
I choose that over using weight because so many factors can alter the weight of the materials. One batch of saltpeter may be as dry as a towel hanging in afternoon summer sun, the next one may be slightly damp enough to be unnoticeable, but yet, will throw all my weight calculations off orbit because of the latent moisture.