O.K., now I show my ignorance! What you are referring to as reinforcement on the breech end, I figured was normal. I have been told that this rifle has "shoe lumps" and I took it to mean that the lumps were part of that piece and was brazed onto the barrels. That reinforcement is like a saddle that the barrels are laid onto and brazed and of course, the bottom of this saddle has the lumps. None of my reference books show the differences although I know how to ID chopper lumps and mine does not have them! Curiouser and curiouser! Lee.