Recently when cleaning my 22/45 MkIII Hunter I noticed something strange in the bore. I usually run a brush through a couple times to loosen up the grime, and I noticed that the brush hit a 'loose' patch near the center of the barrel where there was a very noticeable drop in resistance. Upon inspection with a bore light, I noticed a ring around the bore about halfway down the barrel where it appears some material is missing. The ring is symmetrical, and approx. 1/8" to 1/4" in length.
Taking pics of the bore is tricky, but here is what I came up with:


Since the Hunter has the heavy, fluted bull barrel, I was not overly concerned about safety and have continued to use it without incident. The gun still shoots better than I do, so it's hard to tell if accuracy has been affected.
Any advice appreciated,
CM