I just began cleaning an older, new-to-me .50 cal. CVA barrel that my initial check with a drop-in bore light made my heart sink a bit, appeared to have rust and some scaling. I liberally dosed the barrel, standing in a large bucket, with Fluid Film and let it stand for a couple of hours. Put a brush into the barrel - (brushes scare me) - pushed the brush in, pulled it out, checked that it was still firmly screwed into the TOTW steel range-rod, repeated a couple of dozen times and then began to clean with patches. Dirty, rusty returns, used .45 cal jag, cotton gun patches doubled and after a couple dozen swabbings, I am still getting a slight rust staining - more to do. Dropped the bore light in, mild generalized small pits but good rifling and bore in pretty fair condition. I bought the Fluid Film after reading a lot of very positive comments about it recently. I also use Barricade, and like it.