brown smudge coming off when cleaning surface of 870

[tom]

I've noticed that when finishing cleaning, I use Ballistol and a lightly oiled patch to wipe down my wingmaster. Usually I get a very light brown smudge that comes of from the outside and it puzzles me, because to me that indicates rusting - but the gun hasn't even gotten wet and I religiously clean it after range time. There is no visible rusting or brown color on the surface before wiping or after it.

I found this article on another forum, discussing this:

http://thefiringline.com/forums/archive ... 32243.html

There they discuss it's "oxidized blueing" and the final post mentioned this : "I've done some further research and it appears this is a type of blueing rust that is rather common and rarely noticed, as it doesn't show up until after cleaning. Further, it takes a really good penetrating oil to remove it, and therefore (since most don't use oils that are great at penetrating), it's not noticed."

I'm curious, is this common in blued guns or should I perhaps be using some other oil when wiping down the shotgun from the outside?

[MStarmer]

Ballistol is fantastic stuff, I would imagine that along with minor rust it's also removing dirt and anything else that has accumulated on your weapon. Is this something that just started showing up, or is it something that showed up using Ballistol? It may be removing old trace lubricants as well. Even BreakFree and others over years gets gummy and hard to remove.

[Synchronizor]

Gun bluing involves generating a layer of black iron oxide (Fe3O4), which is a different compound than red iron oxide (Fe2O3), AKA rust. The black oxide is more stable and adheres better than the red; but oil is required to really seal the metal against the environment and effectively discourage corrosion. If you're not oiling your gun, especially before storing it, you may be seeing trace amounts of red oxide that has formed on the metal.