As already suggested by Fretless, I use Hornady One Shot Cleaner-Lube. It is black powder compatible and, therefore, doesn't have to be cleaned from the gun when switching between propellants. If the carrier ever gets gummed up during a match, I use Ballistol to get it going again. But, once using Ballistol during a match, the gun quickly gums up again. It must be continuously re-lubricated every two stages after that. Wet lubes are like a magnet to carbon and dust, so for me they are emergency use only. Fortunately, Hornady One Shot will get a gun through many matches with smokeless powder and most of a single match with black powder. All this is dependent on wind (dust) and humidity levels.