As far as cleaning goes I’m cheap so my absolute favorite is dawn dish soap and hot tap water.
The corrosive element is salt. Salt dilutes with water. So rather than use a small amount of expensive cleaner, I will use a large amount of cheap water.
I made a little tool with a sewing needle to clean the tiny hole of my breech plug in between shots.
When I am out shooting, I use a mix of isopropyl alcohol and water to swab the barrel after every shot. The water clears the fouling the isopropanol helps it to evaporate.
I keep in mind it back when these things were invented they didn’t have hoppes black powder cleaner or anything like that.
Just remember to oil your rifle after cleaning with soap and water.
Many law-enforcement agencies use simple green, and then oil. That’s for modern firearms, of course.
Again, with black powder, the danger is the salt.