I have recently inherited a 1907 LC Smith 12 ga. side by side shotgun, and when a friend of mine, who has some gun skills, examined it, he noticed concentric circles as you look through the barrels. Not rifling, just about four rings that are noticeable as you look through both barrels. The same effect is visible no matter the lighting conditions.
This is an armored steel barrel. The shotgun has been used up until the last several years, so it's a functioning firearm. Anybody know what these circles might be and are they a problem?