Even stainless can corrode.
Ever seen one of those rusted up "perfection" pistols? People try to blame those on sweat, salty environments, etc. The cause is lack of surface protection. The finish is better than bare metal but even those special finishes will corrode if neglected long enough, often enough.
Either wipe it down with an oily cloth or put a couple coats of good car wax on it (hard to do in the chamber/barrel, but oil works just fine where you can't wax. I waxed three P01 magazines last summer. The rest of the summer, when I'd come in from outside working, I'd pull the magazines out of the pistol and the pouch and wipe the sweat/rain, etc. off with a paper towel and put them back in the cabinet till the next day, next trip outside. Those blued magazines would look shiny/new after every wiping to dry them off. When I got the XD 5" Tactical I waxed those stainless magazines and even waxed the outside of the stainless steel slide.
Quite true, there many different grades of stainless, the higher the grade of stainless, the more rust resistant it is, because it has less carbon in it.. And I'd guess gun manfacturers aren't using the higher grades. They want something while stainless, is easy to machine easy on the tooling, and isn't terribly expensive.The S&W M&P is a good example, as S&W choose to have the barrels and slide nitrided..this is a bit tricky as stainless and nitride don't play well together..
I've been using Renaissance wax on my blued mags, I put a coat or two on every couple of weeks, so far so, good, we'll see how well it does when summer comes.. I think it'll work just fine..
As far as rusted up Glocks go, I've only ever seen one or two, and both of them were badly abused..Myself, I'm kinda against oiling the bore of a barrel on a carry gun.. the reason for this goes back to rifle shooting, but it applys here.
When you shoot a cartridge, the case expands to the chamber wall and stops, the case also gets a grip on the chamber wall. By doing this, this distributes the pressure that 's created evenly around the chamber. When you introduce oil in the chamber, and don't wipe it out, the case now can't get a grip on the chamber wall, and all of the pressure is now directed back towards the breech face. Just remember, a 9mm round is considered a high pressure round, look at the CUP it develops, and it's not that far from a 30'06..This is why I don't leave oil the bores on guns I intend to carry that day, if there's any in there from storage, I wipe it out first.. Why put extra stress on the gun for that first round? This is mainly why I like nitride, with a miminual care, cleaning after shooting etc, wipe it dry, and you're good to go. If you take just basic care of a pistol with a nitrided barrel you'll likely never have a problem..especially if you live in a humid climate..Really, when you think about it,there's no reason NOT to have the barrel of a pistol intended as a ccw protected with something besides oil..
