I've got one of the "American Browning" Model 11's. I bought it cheap and just got around to tearing it down to clean it up. The only real issue (other than the springs) is that the barrel extension is able to unscrew by hand. There's no damage to the extension or the barrel and the threads are fine. How is it supposed to be attached? Peened? Soldered? Any advice on this would be appreciated!