John: you may well have 'British Laminated Steel' barrels, and "3 Bell" is likely 3 Iron Laminated. Unfortunately, the Belgians called Twist 'laminated', and c. 1880s US makers labeled One Iron Crolle 'laminated' (usually one grade above Twist and one below 2 Iron Crolle) Check out the pics and descriptions of each on the 'Damascus Barrels' album
http://www.picturetrail.com/gallery/view?p=999&gid=16082038
You can also access the 'Parker Damascus' and 'Colt and Remington Damascus' by clicking on 'Album List'