Erat

About 40 years ago my parents bought a Mossberg 500A shotgun for some reason, and then never used it. It's literally still in the original box and as far as I know has never been fired. But it was really just neglected all those years and now it has pretty bad rust on the barrel. Do you think I could clean up the rust myself, maybe this can help me https://rustconverters.net/drx-rust-remover-ultimate-review/ or should I take this to a gunsmith to have it restored?