forerunner to 1100
The model 48 Mohawk and Model 58 sportsman were Remington's semi auto offerings prior to coming out with the 1100 in the early 60's. (There was another model, the 878, but I'm not sure when it was introduced). I beilieve they use an spring recoil system vice a gas operated one. Gunsamerica.com may have barrels listed for it. Also, Numrich Arms may have barrels available.
You can check on Remington's website to see the exact dates of manufacture for the Mohawk. It is under their history section.
vr Charlie