The compound mentioned in "The Pictorial History of the Underhammer Gun" by Hershel Logan mentioned a percussion composition.
I used that formula and the components there were available to me to make compound for percussion caps when store bought caps
were not available to me in the 1970's.
5 parts Potassium Chloride, 1 part sulfur, 1 part charcoal.
I was able to source the Potassium Chlorate at an Apothocary's shop(Pharmacy), sublimed sulfur (flour of sulfur) and I ground up charcoal briquets as I did not want to make charcoal as
not was available locally.
I mixed the solution in a slurry, and used it to inside the percussion caps I made from steel pop and beer cans (no aluminum in Canada in those days). I drop of 'liquid' in each cap. After drying
in the sun, they were VERY hot caps. Of course due to the chlorates, they were corrosive, just like the late 1890's primers, using the same solution. (caps made with a Tap-O-Cap die)
I was informed this formula was outlawed as it sometimes became unstable. It worked for me. I drilled a 3/8" hole, about 3/8" deep out a solid bullet from a Minnie mould 'ball', filled it with the
dried, but powdered compound then a smear of BW over the top. 3 shots would cut off a green 12" aspen tree.
I don't make the solution any more & haven't since about 1978. Old friend Lester H. Hawkes said one day, ever thought what might happen if that stuff went off inside the bore? That's when I
stopped making it.
edited: chlorate instead of chloride: