I use this breech brush . . I spray the threads with solvent 1st and let it work its magic for a min or 2 . Then I put a 3x3 cloth shotgun patch over the brush with solvent on it . Then screw it into the breech and let it follow the threads. Do that with a couple patches . Then hit it with a dry patch and its shiny clean . I actually clean the powder and projectile seating area at the same time with the same patches by pushing the brush deeper in the barrel once it gets past the threads . Then screw it back out following the threads .
That fire channel brush is amazing how much crap it gets out of the breech plug fire channel . I never want to be without one of those . Amazing little brush .