That is a beautiful example of a Model 29. but, it is a matted barrel, not a milled raised solid rib. Here is a diagram from a 1939 vintage Model 11/Sportsman brochure --
One thing that has amazed me is that Remington charged the same price for a Matted Top Surface of Barrel as the did for a Raised Solid Matted Rib --
When the Model 870 Wingmaster was introduced, the Model 870 AP "Standard' Grade had a plain barrel. The Model 870ADL "De Luxe" Grade had a barrel with a matted top surface. A ventilated Rib was an extra cost option. With the introduction of the Model 11-48/
Sportsman-48 and the Model 870 there is no more mention in the Remington catalogs of ribs being manufactured integral with the barrel.
