I don't know what the finish is called but I sure know what you're talking about with the 870. My oldest son has had one for a few years and that gun is rusting like no other. He also has one of the cheap Savage package guns that he treats no differently. What ever the finish on the Savage is, he seems to be having no trouble with it. I just bought an 870 Express for my youngest son to use. (It hasn't had one shot fired through it yet...damned shame!) Anyhow, I was planning to apply a very liberal coating of oil and pray it doesn't rust away!