I haven't tried the stuff mark Whiz mentioned, so can't comment...RE, for actual black powder, NOT substitutes - the "other" types of solvents: I have found that Hoppe's No. 9 Plus is about useless. The TC stuff (no. 13??) is better, but not much. Shooter's Choice Gel works OK. There are other "exotics" I haven't tried. PLAIN, OL' HOT WATER is hard to beat. For a complete, thorough cleaning, at the end ot the season before putting a gun away, I pour two quarts of BOILING WATER through the bore, DRY IT IMMEDIATELY WHILE HOT, then oil with Break-Free CLP right away!! Next day, I swab it out with two patches just dampened with Break-Free CLP. Using this method, I have NEVER HAD ANY RUST IN A BORE. Have been cleaning this way for the past 40 years (before Break-Free came on the market, I used genuine sperm oil given to me by an old muzzleloading rifle maker in Indianapolis IN in 1960.)