Originally Posted by dpadams6
That's from the barrel sliding thru the slide. Its on top and bottom. Our Dept. Guns at our annual inspections showed barrel wear. Not quite that much, but some were close to that. Just make sure to grease the outer barrel and inside the end of the slide. I'm sure you wont have any problems. We never did.
That's completely normal, with Sigs it helps tremendously if you use a grease like "Slide Glide" especially if you going to be doing some extensive range shooting say 250 rounds + per session.