Talking of old case cleaners, a friend bought some home-brewed concoction at the Aledo Gun Show five decades ago. Cheap and guaranteed to clean, the directions were to leave the cases in for fifteen minutes, then thoroughly wash cases in clear water and use baking soda to assure all the cleaning agent was consumed. This had a bright blue color with a thick oily appearance.
The warning was to use it only in glass containers and pour it carefully back in the jug. This cleaned cases quickly and well. The other warning by the man at the table was to not get it on clothes or table top.
Having a chemistry major, my friend wanted me to test it and see what the ingredients were so he could make it at home. My suspicions were confirmed, Aqua Royal and copper sulfate to drive the reaction toward keeping the copper in the case and not leached into solution. Aqua Royal is a mixture of concentrated Sulfuric acid and concentrated Nitric acid. Not a mixture for someone outside of a laboratory to use.
My report was to quit using it. There was no way to make this solution at home unless you had a laboratory setup with safety features. We then recommended to the people running the show to speak to this person and have him cease selling it. This was done.
Today, I use tumblers with lizard litter (walnut shells) bought at pet stores on sale. And for black powder cases, the steel pins with Dawn detergent and Lemi-Shine additive.
Country boy from Illinois, living in the magical Pacific Northwest