Your barrels and for-end iron date it to 1909. I believe that the beavertail wood was added to it later. The receiver's serial number dates it to post 1945, and could be from parts left over when Marlin bought them out in same year. If that is all that is stamped on the receiver's water table, but, I don't believe at that time they were making the Regular frame then. Is there a number stamp like 00 and then E on the receiver's water table? If so this would date it to 1906.
This has nothing to do with the rib, but I am curious about the serial number.
