Will shotgun shells rust the inside of the magazine tube eventually?

[monduconstruct]

Hi Everyone,

So this morning I was thinking ... I have 4 rounds of 00 buck sitting in my 870P's magazine at home, and I may not go shooting for a month or so. So the metal of the shell is definitely in contact with the metal of the magazine barrel, and it only makes sense that two dissimilar metals placed together will induce a galvanic action, which could corrode one or the other metals, as one acts as an anode and one as a cathode.

So I pulled up a galvanic chart and (assuming the shell is brass and the barrel is steel) realized they're pretty dissimilar. The brass appears to be quite a bit more cathodic than the steel, and if I remember my chemistry right, electrons will flow from the anode to the cathode, or from the steel to the brass. So the inside of the magazine tube will develop rings of corrosion where the brass head was in contact with it.

I'm interested to hear if anyone has some real-world knowledge of this, and testimonials if this really occurs or not. If it is a legitimate concern, how do people leave shells in their HD guns? Has anyone ever shined a flashlight into the tube that is typically left with shells in it?

 

[MAX100]

You should clean the inside of your mag tube periodically. Give it a very light coat of oil.

If a galvanic reaction could happen it would take a "very" long time under extreme conditions.

The problem you will have if you leave shells under pressure in a mag tube for long periods is the plastic ends will most likely flare/spread causing feed problems. So check them every month or so.


GC

 

[ReloaderFred]

Most, but not all, modern shotgun shell manufacturers use steel for the base metal on their plastic shotgun shells. Only the "premium" shells still have brass bases. Some wash the steel with copper to make it look like brass, but a magnet will quickly tell you which it is.

I've left 00 buck shells in a shotgun for a couple of years without any rust appearing. You do need to inspect the cases and make sure they don't squash, as MAX100 mentioned, and clean the magazine tube every so often.

Hope this helps.

Fred

 

[paducahrider]

Howdy!
If the gun is stored in a high humidity location, where temperatures can drop below dewpoint, moisture will condense on all surfaces. When two surfaces touch(like a mag tube and a sg shell) the moisture is likely to cause more corrosion at those points.
Some plastics are also somewhat hygroscopic(absorb moisture), and, if they stay in contact with steel, are more likely to cause corrosion.
I had that happen once, by leaving some dummy rounds in a shotgun.
It pays to check, clean and lube periodically, and how often will depend on your particular locale and storage methods.
Trial and error will help determine how often is needed for each application.
Thanks for your time.

 

[monduconstruct]

Thank you guys very much for the responses. Very helpful information. I live in a place where going shooting is very difficult, so I want to make sure I'm storing the gun properly so it's ready when needed.

Interesting about the copper plating on a steel shell head. Copper is galvanically very similar to brass, pretty much the same actually. I'm surprised more people don't run into this. Perhaps the manufacturers of the mag tubes considered this and coated it specially. I will certainly take everyone's advice and watch for shell distortion and also clean out the tube next time the gun is apart (tomorrow most likely). I had it apart a few weeks ago and never thought to coat that with a light oil. Thanks!!

 

[Fred Fuller]

It's as necessary to pull maintenance on the inside of the magazine tube as it is on any other part of a repeating shotgun. But lots of people ignore it for long periods of time, and still get away with it. Why take the chance? Clean the shotgun when it needs it, and that means the inside of the magazine tube too.

lpl

 

[JNewell]

Echoing and amplifying Lee's point, I'd be very careful not to leave any excess lube in the magazine. Among other things, it will attract and/or hold dirt and grit that you don't want in there. It could, under really bad circumstances, also affect primer reliability. At the most, unless I lived or worked with the gun on the water, I'd run a very lightly oiled patch through the tube and then I'd run a dry one through. A very thin film will remain and that is more than sufficient.

As a sort of related concern, going back to your earlier discussion about extension tubes, I meant to mention that there is another rationale for a magazine extension that has little to do with magazine capacity and a lot to do with ammo integrity. Magazine springs tend to be quite strong, with good reason. If the magazine is fully loaded, it's possible for the spring pressure to cause issues like crimp failure and bulged plastic shell casing (enough to cause feeding failures). If you install an extension and then download the tube by one shell, you reduce the odds of that happening. And, you should cycle new ammo into the gun periodically so you don't wind up with your defensive loads being the oldest shells in the house.

 

[zhyla]

Are mag tubes finished on the inside? I haven't really looked at my 590's tube much. I don't recall seeing shiny, bare steel there.

 

[4thPointOfContact]

I'd worry a Lot more about mushrooming the shells, like MAX100 mentioned, I've actually experienced it happening. The rust? Not so much.

 

[Virginian]

Galvanic corossion requires an electrolytic bridge, like water. Keep it in a relatively dry place and swab the inside with RemOil occassionally and you won't ever have a problem.