"...I think it used to go by the name of Clean shot..." which was similar to a powder known as Grand Canyon I believe.
A guy at the range gave me 2 pounds of Grand Canyon about 8 years ago. I thought it was very nice of him, until I tried it out.
It was very consistant. Unfortunatly, its consistency was being very inconsistent. Folks found it was best when it was crushed in cartridges but there was no way to get enough crush on it in a muzzleloader.
I let it sit on a shelf for several years and it turned into a large lump. Being unusable, I burned it in my back yard. It didn't even burn very well.
Back to the sulpher in Pyrodex. IMO, it is added to produce good smelling smoke and perhaps retard the speed that the basic powder burns at.
Nothing like the smell of Black Powder in the morning, Ah says. ::