The name of it is actually CVA BARREL BLASTER WONDER GEL SOLVENT
, and the label also says that it's a "concentrated gun cleaning gel" and that it "removes rust without harming barrel finish".
I've heard that it works especially good to clean up gun barrels that have been neglected. When a gun barrel is encrusted and looks like it should be thrown out, that product can do a tremendous job cleaning it up to look almost like new.
Close up photo: