I have an 870 Express 12 gauge that was new when I bought it a couple years ago.  It is one of those "I shot it a couple times and it hasn't been used since" type guns.  When I shot it, it wasn't raining or any bad weather.  I put a coat of oil on the outside, wiped it dry, and put it in the safe.  A couple months late the barrel had some run on it. The thing looks brand new and it has rust problems.  I've kept it oiled and in one of those silicone socks in the gun safe.  I have problems worrying if I don't baby it, I'll find rust on it.

I have the opportunity to sell it at wholesale and buy a used Mossberg 590A1 that is in pretty good shape at retail.  I'm tempted to do it because of the rusting issue.

Anyone have any opinions? Are 870s known to have rusting problems? What about 590A1s?

The finish on the New 870's suck...
And rust is a on going problem with them

Pretty sure that is a feature on the base models.  My 870 police magnum rides in my patrol car trunk here in Florida.  Never a bit of rust.  I spray it once a month or so with barricade spray.  Never an issue.  Every express I have had rusts even in my house when oiled.

Have it coated with one of the trendy coatings.  Mine has Gun-Kote on it.

Here is another one with the coating:

So you either key it wet (with oil you can see) or you get rust?

Yep, this one was just sitting in the gun safe.  I even oiled it good before I put it away because I knew it would be some time before I shot it again.  That Mossberg is looking better all the time.

Yeah mine used to surface rust if you got misty eyed at a sad movie.

I got the surface stuff off and applied Eezox. I’ll be damned if it hasn’t developed any rust since. It’s been a LONG time too. If I ever clean more than a boresnake through it, I can guarantee Eezox is going back on.

That's why I bought this version:

ANY Remington with the "express" label has a shitty finish, and will flash rush unless you keep it well oiled.

A couple of things, first, the salt blue/black oxide finish on the Express model is no better or worse than any "traditional blued" or parkerized firearms I have owned for the last 50 or so years. They all require a certain amount of diligence in order to keep rust away. Even my stainless vaquero will show signs of rust if I neglect it after carrying in the summer. I own a vintage A5 browning with a beautiful blue finish and without question all my Express models will rust less than any of my blued guns commercial or military. I have a half dozen parkerized weapons including a 870P and it shows more rust at times than my 1987 Express magnum.  Short of my 5 AR15's, a 1958 Irish Enfield, and my Glock, it has been more maintenance free than any of my firearms. I have owned 4 870's over the years, 2 of which have been used extensively hunting ducks in flooded timber; a Wingmaster and the 87' 870. I'll give you one guess which had to be field stripped and cleaned every night, and which I left in the case on the bottom of the boat.

Second, I'd take the silicone sock, put a bar of soap in it, and send it as a care package to the local jail. It will be far more useful. Silicone is touted as being for the most part "hydrophobic". However, depending on temperature, humidity, air circulation and how long it stays on the firearm it will eventually trap moisture. I used one on my A5 in my gun safe and quickly tossed it. Won't make that mistake ever again. Don't get me wrong, they may work well for transport and very short stints in storage IE cargo holds etc., but not good for long term. The best medicine for keeping rust off your firearms is diligence and the KISS principle. Wash your hands prior to handling with a simple dish soap to get the oils and salts off your fingers and palms. Wipe you guns down every couple of months using a good synthetic oil(I use mobil one motor oil). Stay away from exotic treatments; they tend to be way over priced when the first two work as well if not better, and whole lot cheaper. Don't use WD40 as your primary treatment and lubrication. It does a good job of displacing water, but can also push it into small places and trap it. I'll use it after being over water or rain/snow/icey field conditions. Let it set for a while, field strip, and then clean with a brake cleaner or kerosene. Let dry, then oil liberally and wipe down. My dad and I learned the hard way about 40 years ago with WD40 on a Iowa pheasant hunt, under snowy -20 degree temps. WD40 gummed up our A5's so badly it turned them into single shots.

Last, if you do get some rust, use a stainless pot scrubber with a good synthetic oil to remove the spots. It looks a lot like steel wool but softer, and less likely to mar or remove sensitive blueing. They can be found in most grocery or hardware stores. Oh, and don't buy the ones in a gun shop, you'll pay 10x the price for the exact product found on the Dollar General shelf. I'm all for supporting my local dealer, and I spend a lot of money on this disease in their presence, but I do draw the line on some things.

I may have over simplified this a bit, but it has served me well for many decades. As usual YMMV

Best regards

Rod

I have seen this with more than a couple 870 EXPRESS finishes. As others have speculated, I believe the source of the problem is residue left in the matte-blued finish from the factory.

What worked for me (and for a friend) was to detail strip the gun and wash all the matte blued parts with hot soapy water then rinse everything with a 80/20 mix of distilled water and Ballistol. Allow to dry in direct sunlight or help it along with a hair dryer. Finally, apply a coat of GOOD wax. I like Meguiar's carnauba-based car wax applied super thin and then buffed.

I appreciate the time you took with your suggestions, Rod, but this is the only firearm I've ever had this problem with.

Let me take that back, I have a Ruger P-85 that I got back in 1985.  Yes, it went to the factory for the warranty work to turn it into a P-89.  I kept that in the back of the car in a little safe.  I oiled it a couple times each year, never with a problem.  The at the range, the slide broke.  Yeah for Ruger, they sent me a return ticket and gave me a new slide.  Boo to Ruger because I have trouble with that nice, new upper slide rusting if I don't keep it stored in the safe slightly wet with oil.   30 years that old one went without problems.

Welcome to the club!

Why are you on a forum instead of doing this? What is wrong with you?

I originally bought a Remington 870 and I got rid of it for a 590a1. Haven't regretted it. Get a bayonet with it as well.

I keep my 2013 vintage express wiped down with CLP and have never had any rust issues, but the finish is crap on it and will scratch off with your finger nail.

I had the same issue with an 870. Thin coating of rig fixed it.

https://shop.brownells.com/gun-cleaning-chemicals/oils-lubricants/rust-prevention/rig-universal-grease-3-oz--sku167400274-31842-61038.aspx?cm_mmc=PPC-_-Itwine-_-Bing-_-167-400-274&msclkid=29ea6154c56e1582bca73dbc69ec70c9

Do you have to keep applying it, or does the "rig" eliminate it?

My Remington receiver is also rusting a bit.  I tried Gunzilla and it didn't work.  I just put Hoppe's gun grease on it while in the safe.

It works for long term storage with one coating, I also have a rag that has a bunch on it I wipe stuff down with before I put stuff back back in the safe. Think of it as super thin, non gross cozmo.

I've found with my 870 that after a while it eventually "blued" itself and the rust stopped appearing. I'm not sure if it was the rig or if it developed a patina but eventually it did stop.

The gun smith that turned me onto it was originally from Alaska and said it was popular with the locals for long term storage and use in the harsh/wet conditions.