Hmmmmm, never used that Lucas solvent. Are you shooting black powder subs?
I do use any carb cleaner spray, from the chambers to the far end of the barrels....followed by a long brass brush up and down 3 -4 times. Usually that breaks the plastic wad debris, carbon, etc...., then one to three cloth patches coated with Hornady one shot gun cleaner and lube. from the chambers to the end of the barrels.
How old is this SxS?