I keep some h20 in a well cleaned out nasal spray bottle & keep that in my range box. I use it to douse the bore and run wet patches thru it & the bolt face, then clean w/ conventional cleaners, then oil. I use 5-20w synthetic motor oil as it has more "stick" to it than say Rem oil and it seems to have some cleaning power of its own. It is also substantially less expensive than commercial gun oils and a quart lasts for years. About every other range session or so I use Wipe Out foaming bore cleaner instead of Hoppes, etc and that really gets the crud out. I never thought about black powder solvent...that seems logical and when I run out of the Hoppes in my range box I will try that.
Invest in precious metal...buy lead \m/