Like the manual and everyone else says, I use drill bits to clean and remove carbon build up. I do use a tap wrench to hold my bits while I clean. A fellow emeber over at Doug's suggested a excellent way to "speed clean" you plug.
He said he took his drill bits and ground off the tips untill they were flat and would not cut or harm his breach plug. He then put them in his battery drill and set on low RPM cleaned out his breach plug. IIRC said from start to finish was but a few minuets.
I usually soak my BP over night in Big Eds befoe I clean it.
My Breach plugs have bushings in place of vent liners.
I am also told there are some killer good carbon disolving solvents out there that will realy cut cleaning time just never tried any.