Antimony trisulfide source, beware nitro headache
The last time I got antimony trisulfide, I found it at a ceramic supply place. It is used for making metallic black paint and glazes for pottery. A few other firearms-related chemicals can be obtained from ceramic and pottery supply places.
I have used the Frankford Arsenal Number 2 primer mixture, which was used by the U.S. military until about 1953 when General Julian Hatcher's 35 years of screaming into the Army's deaf ears to use non-corrosive primers was finally heard.
There is nothing sacred about the Frankford Arsenal Number 2 primer mixture (its recipe is listed in Hatcher's Notebook and some other places), use whatever primer formula does the job! The one just posted recently, and how it is used, sure sounds like a winner to me!
I have used smokeless powder dissolved in acetone and/or lacquer thinner for various things. Great stuff and works well. Remember that double-base smokeless powders contain somewhere around 30% nitroglycerin, which is also a commonly used medication to RAPIDLY lower blood pressure. Be very careful about getting any double-base smokeless powder dissolved in acetone or lacquer thinner on your skin! Nitroglycerine goes right through your skin, meaning fingertips and any other place on your body, and it doesn't take much to have a physiological effect. A strong cup of coffee somewhat counters the effect that nitroglycerine has on lowering blood pressure, but nitroglycerine poisoning is no joke. The first thing you may notice is a headache that is so bad it might send you to the emergency room! Once there with the worst headache of your life, you just may be given a CAT scan looking for a brain aneurism, since the sudden onset and intense pain resembles that deadly condition. Hopefully your very low blood pressure will be noticed by then. My dad's maternal grandfather was a hard rock miner in the Old West, in such places that included Tombstone, Arizona; Park City, Utah; Silverton, Colorado; and Coeur d'Alene, Idaho, from the early 1870s until about 1905. His specialty was working with dynamite (he made it to 90 years of age), and he told my dad about the dreaded "nitro headache" and how to avoid it by not coming in contact with even the tiniest amount of nitroglycerin - the dirtiest of dirty tricks was to contaminate a doorknob of someone "who done you wrong" with some "nitro". But back to smokeless powder dissolved in acetone and using it to glue stuff, yep, it works darned good! Just don't get any on your skin is all. Nitroglycerin is not soluble in water, so rinsing with plain water won't work, rinse off with 91% isopropyl alcohol, Dawn dish detergent, mechanic's hand cleaner, whatever.
Have fun!