If a half-round breech scraper is used on a ramrod down a particular .62 cal fusil, it hangs up down in the breech as it's twisted. Shining a flashlight down the bore, "something" looks to run left-right across the breech. I was able to snap this photo. The "something" is the dark horizontal line at the bottom of the barrel. What is it? I'm guessing it could be some type of chamber related to the touchhole. Thanks.