De nada.
It's amazing how long those pivoting extractor springs can last, isn't it?
As far as the polishing of the chamber? I can see that happening with the occasional barrel produced on the old equipment.
We discovered that every once in a while we would find an occasional high spot on some of the early production 3rd gen guns when it seemed as though there might be a tight chamber. The head armorer at the time used to use a set of finishing chamber reamers to knock off the high spot and resolve 'tight' chambers. It cleaned up the barrel leade area, too, but it could also ruin a barrel pretty quickly if someone unfamiliar with how to properly use one tried it.
I've also always suspected that a Dremel should require a 10-day waiting period when someone has a hankering to 'fix' a gun with one.
