Got bitten by the rem model 12 bug a yr or so ago. Now have a 12c Octagon bbl from the mid teens. Great bore (which is unusual), some freckling (that's rust on your guns, freckling on mine), and now carries a tang peep sight. Great fun to shoot. I did find out that you should not shoot hi velocity rounds in the model 12"s. Bolt have been known to break. That was the reason the 121's were designed.
Charlie