I recently sold an Inox (stainless) Beretta 92fs to my future brother in-law.  I had the thing for two years without any problems.  I barely even oiled the thing, and it would sit for long periods of time (I never shot it, that's why I sold it).  When I sold it to him two months ago it was in perfect condition with less than 200 rounds on it.  He called me this afternoon and informed me that it is rusting.[thinking]  He braught it over to show me this evening, and I was astounded.  This thing is covered with little pits of rust.  As if that wasn't bad enough the front strap and trigger gueard are somehow stained black.  What the heck happened to this thing.  He's been using a Kleen Bore silicone impregnated cloth on it about every two weeks.  He keeps it in a drawer with a Master trigger lock on it.  The only other things kept in that drawer are a set of keys and some vitamin suppliments in plastic containers.
I can somewhat understand the rust, I know that stainless can rust, but he swears he did everything I showed him maint wise.  What really confused me is the staining of the aluminium frame.  It almost looks like the rubber Hogue like grip is breaking down and imbedding itself in the pours of the aluminium.

I need help in suggesting what to do with this thing.  Neither of us feel comforatable enough in trying to fix this problem ourselves.  I told him to call Robar and get a price on a cleaning and NP-3 finish, but I think that will be a little more than he is willing to spend on this gun.  Any suggestions on the source of this problem and a solution would be very much appreciated.  I know it is not my fault, but I can't help but feel bad about this.  This was his first handgun and now I fear he will be discouraged by this.  It's nice having a person to go shooting with on a regular basis.
Thanks in advance for your help.
Ed.

Did he store it in a leather holster?

Can you post a pic. Would be interested in seeing it.

Not stored in leather, and my digital camera has crapped out.  It almost looks like someone sprinkled cinimon on the stainless parts and the staining on the aluminium looks like spider webbing.  I can't really figure out how else to explain it.

Try a product called corrosionx, it the best. their web site is [url]www.corrosionx.com[/url]

I've heard of this on some Ruger stainless slides because their slides are cast and porous.  But never on a Beretta who's slide is machined from a solid block.  I've kept mine in a safe for 2+ years and haven't oiled the outside of the slide.  I figured, hey what the heck, it's stainless.  But I'm going to check it after my AR15.com fix for the day.  I would call the factory.

I bought a new 92fs a little over a year ago. I looked it over real good and even had the seller go get another to look at, then chose which one I wanted. I took it home and put it in the safe with all the other kiddies and didnt have a chance to shoot it for several months. When I went shooting I noticed a small patch of rust on the barrel. it is the portion of the barrel which is covered by the front hood of the slide when in battery. It must have had a bit of moisture on it from the factory or in shipping or ????
I contacted the seller, no recourse. I contacted beretta, no recourse. Basically both parties said "tough shit" I would expect that from the dealer, but not from beretta. Very poor customer service IMO.
About a month ago I was at the range and the guy next to me was shooting his 92fs and after some yappin about guns and such, I showed him the spot where there had been some rust. He then racked his slide and showed me the exact same spot on his where he had rust too.
Maybe a quality control issue on a certain batch of pistols ???

Ask your brother-in-law if he stores it in a fireproof safe.  I had a Beretta 92f and I always stored it with a trigger lock, for years I didnt have a problem.  I bought a Sentry fireproof safe and within 1-2 months those rust pits appeared.  I also stored some cash in there and I noticed that when I pulled it out it was kinda moist.  

To correct the problem I threw in some dessicant and the problem went away but I have to replace the dessicant every couple of months.

Interesting.

I just checked my SS Beretta 92FS (my carry gun for this week) and there are no rust anywhere.  This pistol is about 6 years old and shot about 7,000 rounds.