Boiling water heats everything up so it dries instantly, gun steels don't flash rust like cast iron. Then spray down with Ballistol. I don't know exactly what is in Simple Green but it cuts black powder residue better than anything else I have tried including Windex. Any southern boy can tell you heat is a catalyst. That's why sweet tea is made hot then cooled. Ever try to sweeten Iced tea.

The best thing I have ever used for black powder cleanup is a 1/3 ratio mixture of Murphy's Oil Soap, drug store hydrogen peroxide and rubbing alcohol. It's and old recipe used by match shooters and works like magic. Sunlight degrades the effectiveness so keep it in a dark container. No hot water, no cold water. Just this stuff and then grease it for any storage as usual.

Hot soapy water, in the wife's clean sink, while she watches...

--
Of the Troops & For the Troops

At least the way I used to. I clean with Windex with vinegar and that's it. I found I didn't need the effort and added mess cleaning them the way I used to with buckets of hot soapy water and what not.

(I don't like Simple Green for anything. lol I cough enough from the Balistol, I don't need to cough from Simple Green)

I routinely use about a double shot of Murphy's Oil Soap, in a 3# coffee can of near-boiling water, anytime I thoroughly clean my front loaders. The metal gets hot enough to almost dry itself, or you can dry them off with a hair dryer, etc. The Murphys forms a protective coat that lasts weeks or months. Been using it for ages.

This provides sufficient volume to submerge the cylinder & Barrel (one end at at time) so they can soak a few minutes. With rifles, I pull the barrel off, unscrew the nipple and then submerge the breech end in the solution. Using a tight patch, pump the hot solution in and out of the bore. The very hot water and Muprhys work together as a hellacious crud cutter, combined with the patch.