The barrel is definitely from the teens as the roll-stamp on the top says Remington Arms - Union Metallic Cartridge Co. From 1920 onward it would say Remington Arms Co., Inc. My local Cabelas, a while back, had a Model 10-A from right in the 1920 transition era that carried a roll-stamp Remington Arms Co., Inc. successor to Remington Arms - Union Metallic Cartridge Co.
I was just really wondering if there was any way to convert a Model 10 to handle 3-inch shells? Back in the 1940s and early 50s Arthur Kovalovsky of North Hollywood, CA, would convert Browning A5s, and Remington Sportsman & Model 11s to handle 3-inch shells. See pages 69 and 73 of Shotguns by Keith.
