I think this is really simple: If bare steel (not painted, powdercoated, or duracoated, etc.) gets wet, dry it off. Otherwise it will rust. Doesn't matter the composition of the steel . . . it will eventually rust. It doesn't necessarily have to be dried, cleaned, scrubbed, lubed, and treated. Just dried. A coat of oil is a great idea and will help with future rust prevention. A few of my guns ride around with me almost weekly. If they get wet, they get dried off, but other than that, they usually don't get too much attention and still run just fine.