I have just decided I have been doing this cleaning thing wrong for the last 40 years or so. I pretty near always take the rifle/fowler apart, remove the barrel and lock, put the barrel in a bucket of hot soapy water and go at it. That is no problem for a Hawken or some such with big old barrel wedges and a hook breech. With a long rifle or fowler with thin fore end and pinned barrel, it can be a toss up of wheather is is more damaging to the firearm to disassemble it so frequently, or to not clean it as thoroughly; maybe using blacksolve or some such commercial bore solvent. Just wipe the powder fowling off the lock and oil. Of courrse, I am only talking flinters and genuine black powder.
This thought is connected to the forearm thickness of a future fowler in my own deranged mind. Everyone loves the forearm paper thin and it seems to me to be an accident just waiting to happen as such a piece is very fragile when taken apart for cleaning. Someone posted a busted forearm a few weeks ago. If it had a little wood on it, may not have shattered. I know, not PC. I really am more concerned about function here.
SO how do you clean your ML?