Craig: It is hard to tell from small images, but the 'pit' is a crack, and the 'machine marks' are the crolle pattern
In the above picture, what has caused the rough surface on the top portion of the bore? Previously polished corrosion? Is that spot smooth or rough? I don't get to see the inside of a chamber from this angle and lighting very often, and they usually look to be pretty smooth from the vantage point of the end of the barrel. What I see in that picture appears to be small rings similar to what is visible after use of a Brush Research flex-hone if the bores have not been polished back to mirror. I looked at a 16ga Ideal Grade not too long ago that had opened chokes. The entire bore was mirror smooth from the chamber until the choke taper, at which point I could see the same tiny rings. I own a set of 16ga flex-hones, so I was familiar with the signature they leave behind. Again...I haven't seen many bores from this vantage point, so perhaps those ring marks are common, but it looks like the signature of a flex-hone. I am wrong about most things related to shotgun barrels, so that is likely also the case here. I'm asking the question for my own benefit, and not in an effort to offer up new information.
