Rust on an old 12-41 rifle

[Singer B]

A really good light rust remover is boric acid. It's very mild, will not hurt the finish but it removes every speck of corrosion, even from complex parts. Warm a pot of water and dissolve as much boric acid as it will take. Immerse the part and keep it warm on the stove for several hours. Remove and rinse, it will be spotless.

Thank you!