Originally Posted by
Multigunner
A piece of brass tubing with a slot cut in one side and teeth filed into the end will scrape away the hardest foiling in no time.
I use this method to clean the chamber neck of old military rifles that have had fouling in the chamber neck caked so thick it caused excess pressure due to preventing the case neck from expanding to release the bullet smoothly.
It should work for revolver chambers.
I'd suggest expanding the mouth of a decapped .357 case, filing the teeth in the case mouth, then run a narrow screw through the flash hole and lock it with a nut. The exposed length of the screw could be chucked in a hand cranked drill or threaded into a short rod and turned by hand.
Every so often expand the case mouth again till its a tight fit.
Don't use an electric drill. You need to feel your way along.
The stuff that comes out of a chamber neck looks at first like thin streamers of black plastic like material, then like pencil lead shavings. When you reach bare steel the brass teeth can't cut or dig into steel so they just slide over the steel surface.
Fouling from use of lead bullets can be very hard, much like old dried lead based paint chips.