Okay, so I don't have any experience with corrosive ammo as of yet. I've noticed what looks like rust on my gas system, and possibly minor pitting on my piston. The only possibly corrosive ammo I can think of shooting at any point was about ~50 rounds of surplus stuff I got from someone back in the spring sometime. The last 150 or so rounds I've fired have been Norinco 7.62x51 (stuff in the crate) over the span of a few weeks. It's listed as noncorrosive but I happened to replace my flash hider with a USGI one maybe two weeks ago and I've noticed some of the "rust" sitting in the flash hider slots. Any idea what's going on or a remedy to this? At the moment I'm thinking I should just use a bit of scotch-brite on my piston.

