Strange location for copper fouling?

I've had my LC9S pro for about a year now, and have only shot handloads in it. 124 gr. hornady xtp over 5.3 gr. of power pistol. It shoots great and I have no problems with it, But, whenever I shoot it a copper colored "fouling" of some type appears on the right outside of the slide about 1" behind the muzzle and nowhere else. Not on the left side or the frame, just on the slide. It cleans off easily with Hoppes. So all you "sages of the six-shooter and other things that go bang", what say ye? Anyone have an idea as to the what and or the why?

You MUST post some pictures of that. I have a Pro, and cannot even imagine such an occurrence.

I've seen Glocks with copper anti-seize used as rail lube. Is it possible this could be the source?

No it's not, I've never used anything like that. As far as posting a picture of it, I'm trying but me and photobucket are barely on speaking terms. I'm having a problem going from one window to another, or whatever they call it.

Please find someone to help you post some pics of that fouling. As it stands right now, I doubt what you describe, since there is no visible evidence for it. Or any cause, either.

http://postimage.org/

The easiest way I have found.