The 10ga SB2 shotgun isn't any bigger than an SB2 rifle frame, the opening for the larger 10ga barrel swell is what's bigger, the 10ga shotgun and 12ga USH barrel chamber swells are 1.2" in diameter, all other barrels are 1.1", you can physically put a standard barrel on the 10ga frame and it's been done before, but the barrel must be epoxy bedded in the frame to function properly. SB2 10ga shotgun frames are heated treated, investment cast alloy steel just like SB2 rifle frames, but the side walls of the frame ahead of the standing breech are much thinner than a rifle frame.
Tim
