Soap and tepid water will do the job, with a good bore sized cleaning jag, and cotton cleaning patches. You can plug the touch hole to hold the water in the barrel, or mount the gun so that the touch hole is facing down. Remove the lock, which you have to clean anyway, after every time you shoot the gun. Otherwise, powder residue gets in behind the lock plate, and rusts the lock. There are commercial cleaners that work very well. Some people swear by some of the window washing cleaners, that come in spray bottles. Someone else likes a hand cleaner. Soap and water have been doing the job well for hundreds of years, and while most of us are seduced by ads to try this or that, when it comes down to cleaning the gun well after a long range session, most of us are in our kitchen or garage with a bucket and soap and water. There are kits that attach a small hose to the vent so that you can clean the barrel in the stock without worrying about the water and dirt getting under the barrel, or into the lock mortise. Check the suppliers listed here under Member Resources, at the top of the index page to the forum. If you allowed crud to build up, you will want a bore sized brass or bronze cleaning brush to use on the barrel to break up and pull out the caked crud. Otherwise you have to soak the crud in warm water and soap for an hour or so to dissolve the crud in order to remove it.