For hard-to-clean spots with baked on crud or small rust spots, my wife suggested I use those dish sponges with the sponge side and scrubby side. We have the blue ones for use with flat-top cooking ranges and are non-scratch. Works great with a few drops of Hoppe's #9 and a few minutes of scrubbing. The scrubby side isn't terribly efficient, but it doesn't leave scratches or swirl marks on my guns, and you can cut the sponge to fit the shape of what you're cleaning. One sponge generally gives me 9-12 sponge pieces.