As a rule of thumb, the DS and I grade had: Fluid steel barrels with straight rib extension, no cocking indicators, round knob checkered stock and a snap on forend with no escutcheon.
Many variations to the rule exist. Higher grade features have been used on DS and I grades. However, I think the more common scenario is where all graded features are found in a gun stamped DS. This might be a situation where they had to filling orders, or maybe a customer wanted composite steel barrels on a DS grade??? About the only stand alone feature I have seen on a DS is cocking indicators. I would wager that nearly all that had composite steel barrels also had dolls head rib extensions. But, I speculate.
With Lefevers, all bets are off. I have seen guns with barrels made from one twist tube and one Damascus tube. Guns with one grade stamp on the frame and another on the barrels. All sorts of oddities.
