Use TEPID water, NOT BOILING HOT WATER. If the water is so hot you can burn your fingers or hand, ITS TOO HOT. Put some liquid soap in the barrel, before you pour the water in it. Set the barrel, filled with water aside to let the soap work chemically to loose up carbon deposits. Give it at least a half hour. Now, pour it out, and put fresh soap and water in it, and use a bore brush to scrub the crud loose from the corners of the grooves. Now, put a wet cleaning patch in front of the bore brush, and work that up and down in the barrel. It will come out gray and Black. That is good. You can now pour the water out. Use clean patches with the bore brush to dry the bore and check for remaining crud in the corners.
When the patches come out clean when you use a cleaning Jag under the patches, its time to oil the bore, and leave it that way. You can check it a few days later.
If you are still shooting that gun with the powder chamber, you are going to need TWO sizes of bore brushes- one for the bore, and the other smaller in diameter to clean that powder chamber. Use a pipe cleaner to clean out and dry the flash channel, behind the powder chamber. You can use isopropyl alcohol on the pipe cleaner to clean out this small tube. The Alcohol will evaporate.
Put a drop of oil on the pipe cleaner, and oil the flash channel. Just remember to flush the bore, and flash channel out with alcohol before you load the gun again.