Even for brass, it seems a little off with the tail. I would have thought that it would have puddled better.
I wonder if it bonded something in place there that has since fallen off. But again the steel looks like it has a depression in the barrel.
With out seeing the gun in hand, is it possible that it was a touch hole that was put in the wrong place, the barrel rotated, the hole filled in and a new touch hole made?