Thanks for the thread reference. I have a reinforced splinter on a standard forearm OE Grade 1907 gun, was surprised to find it there. The only thing I can see to explain the existence of the reinforced lug is that the gun has a factory retrofitted tapered vent rib and the owner may have indicated when ordering the vent rib installation that his gun was to be subjected to severe service as a trap or pigeon gun. I doubt it was to be a trap gun since it was fitted with a new splinter forearm rather than a beavertail. The gun must have had a few miles on it by the time the rib was installed since vent ribs weren't available on doubles until, what, 1924? Also, the gun does not have 3" chambers. I am unsure of whether the barrels or just the rib was replaced and don't know how to tell.