Since 1971 I've used warm water and dish soap in a bucket of water, a second bucket with clean water. Then a dry patch, a second patch with WD-40, and a third with Rem-oil. If I've shot my modern SxS's at SC's with black powder shells, then I use a Tornado brush first to loosen 50 or a 100 shots of crud. I've never had a rusting problem. Paul