The only good idea** in this thread is in 101Voodoo's post. This works in .357 and .44 Magnum chambers. I would change only one thing that he said!
Select a .357 case, just touch the case mouth with your case trimmer
, just enough to make a sharp edge on the outside of the case mouth. Then flare the case to the point that can barely get it into the chamber. Push the case into the chambers until it contacts the fouling ring, then push firmly with your thumbs. It takes only once to chip the fouling ring out. Far easier and quicker than brushes, drills, Chore Boy, etc. Using the case trimmer leaves the case still usable. If you chamfer it to the point of making a sharp edge on the case mouth you have ruined the case for loading as a .357! The edge from using the case trimmer is stronger too.
**If you don't mind spending the money, H Richard's idea of the Clymer de-leader is good too. They are available from Brownells but are a bit pricey. Used to be! Can't find them anymore. Was going to say Sinclair, but that is Brownells now. Guess there aren't that many bullseye shooters using revolvers anymore.