Ed's Red is the duck's nuts for cleaning shotguns IMHO.
Nitro and black powder.
Shotgun bores need a lot of solvent due to the surface area, and Ed's Red can be made up in quantity dirt cheap compared with commercial bore solvents.
...and the 25% acetone component sorts any plastic fouling.
In practice I often use a decent spray of Inox wiped out with a wad of wet-strength paper towel (kitchen paper) when the nitro shottie is in day-to-day use during the waterfowl season, but BP needs more attention. "Never let the sun set on a fouled barrel"!

Pretty sure my BP load is now 80gr 2F under an ounce of Bismuth #3s, although being conservative I started off with 75gr powder. Velocity is a bit under 1000fps.
A very old article tossed up on the web HERE ends with an account of my first evening on the swamps with black powder in a Scott "Victoria" top-lever hammergun.
Hope you find it of interest.