I have a Pigeon Grade built in 1909 that was sent back in 1927 for a second set of barrels. The original barrels were chain Damascus and 27" long. The second set of barrels were 28" of Crown steel. I have a photocopy of the ledger page for this gun, and the second set of barrels and the length as well as the date are added in, but nothing on the barrel material, nor style of forearm. Your fore arm is obviously later than the gun, because the gun would have originally had a banjo fore end latch rather than the later style shown.