I noticed an oddity when cleaning the barrel of my 642 today. When looking in the barrel from the chamber, there is a distinct line/crease about a centimeter in length at the bottom right of the bore. It does not circle around the entire bore, just the bottome right curve of the barrel. Although noticable without a light, it is more pronounced (as an indented line) when shining a light in the barrel. Is this what I've heard described as the "ring" the can be found in many of the non-pinned barreled S&W's? Is it anything to be concerned about, or have others noticed this "ring" also?