The finer things in life grow stronger with age: hard liquor, gunpowder, Vault monsters. The list goes on.
— In-game description
Blackbarrel Cellars is a location on Eden-6 in Borderlands 3. It is where Jakobs family cask-ages their signature gunpowder using old booze barrels to give every shot from a Jakobs weapon the proprietary aromatic profile their customers trust and love.