Eezox, followed by Renaissance Wax.
First, unload the revolver and remove the stocks. Next, liberally spray Eezox into every opening - up the gripframe, into the area around the hammer and the trigger (both hammer up and hammer down). The Eezox should run out of various openings, and most likely you will see brown "gunk" coming out of the revolver. I then wait for the Eezox to dry, and carefully wipe down the revolver. Eezox, when wet, is a solvent. Eezox, when dry, is a pretty good lubricant as well as rust preventative, so there is no need to apply any grease or oil. I like to finish the cleaning with one to three coats of Renaissance Wax.
While the stocks are off, consider washing them in warm water using Murphy's Oil Soap, let dry, then saturate with Pledge Furniture Revitalizing Oil (or other good wood care product), wipe down, let dry, then apply one to three coats of Renaissance Wax (wipe on a small amount, let dry, then wipe or polish off) and finally reinstall the stocks. Make sure to use the right size hollow ground screwdriver for stock removal/installation.
This cleaning regime will clean and protect the revolver from rust, and will frequenlty make a heavy/stiff trigger operate the way a Colt trigger is supposed to operate, or a stiffly rotating cylinder rotate freely, or a tight crane made to operate properly. If something is wrong mechanically with the revolver, of course a cleaning and lubrication regime will not fix the problem.