Stainless does not "rust" as you think of regular steel rusting with a red oxide on the surface that flakes off. If you see red rust it is probably due to some iron particles that have contaminated the surface of the stainless steel and it is these iron particles that are rusting. 304 and 316 are spec'ed for corosive environments.

The only reasonable argument for owning a gun is to protect yourself from the police.