Started shooting BP back in the 70's.
Old timer back then and a book I had, both said rubbing Alcohol and warm water with or with out soap.
I like to use what they likely had back then, so no modern stuff.
When at the range shooting revolver after each cylinder or when starting to get too stiff to turn by cocking, Cloth swab around face of cylinder and pin to clean. If really bad I remove the cyclinder and clean. As long as accuracy is good leave barrel alone.
After 5 or 6 shots with the rifle I do the same.
Then when done thorough clean with warm soapy water. Inspect then lube with 3 in one oil/
Singer sewing machine oil.
My breech plug in 50 cal is a real bitch to remove so I don't.
But the revolver barrels are spotless so I would presume rifle is too. Can't see all the way to the bottom with a light though.
I leave cylinders dry, as I reload with paper cartridges after cleaning.