First off no need to shake the Breecplug to death, Im sure you did'nt but no need to damage the Threads on it.
I also soak mine while Im cleaning the rest of my MLer, either in Hot Soapy Water or some Foaming Bore Cleaner that I got from Wal-Mart on a Close out Deal at the end of Last Season, the Soap and Water will do.
I dont use a Drill Bit on the Fire Channel as I have'nt had the need to as it never gets that bad. I use a small (Wire) Brush that came with a BP Brush Cleaning Set I bought for the Fire Channel and a Nipple Pic to clean the Fire Hole. For the Threads I use a Hard Bristle Toothbrush.
(BP)