I have an original antique LIEGE BELGIAN PERCUSSION BOOT derringer with screw barrel from circa 1850s for sale. It’s a pocket size, in 45 caliber, uses black powder and in great cosmetic and functional condition. It’s just a cash sale as an antique, no need of registration or paperwork. It’s not easily available but I see it was sold around $400 to $500 in auctions. I am also open for trade in with other black powders.