I worked with a mechanic a few years ago when he went to clean his muzzleloader he used either (starting fluid ) like you crank a diesel truck with he sprayed it down the barrel and let it soak 5 to 10 minutes then poured all kinds of black gunk out of the barrel.He said it was also good to soak in and loosen up the brich plug he never had a problem with his gun. Since then i have used the same method for cleaning my 2 muzzleloaders and i havent had a problem as i use to breakdown and soak in hot water but then you half to deal with it rusting if you dont get it oiled really good i spray the whole can in mine.Air dry for a little while then its clean or put a cap on it and use it for a flame thrower.Which ever you prefer.
STARTING FLUID!!! Holy Moly.....................highly explosive stuff right there.
It also evaporates very quickly................might as well pour gas down the pipe and let it set. I would not recommend either to anyone you like.
I have used brake parts cleaner on a patch to get a stubborn spot cleaned up, but in small amounts.
“Two things are infinite: the universe and human stupidity; and I'm not sure about the universe.”
― Albert Einstein