From the introduction of a solid rib for the Remington Autoloading Shotgun in the 1908 Remington Arms Co. catalog through the last Remington Model 31s in early 1950 all Remington ribs were milled integral with the barrel -- Model 11, Sportsman, Model 10, Model 17, Model 29 and Model 31. For some reason Remington only offered ventilated ribs on 12-gauge target guns, 30-inch trap barrels and 26-inch skeet barrels, in their pump guns. For the Model 11 and Sportsman autoloaders both solid ribs and vent ribs were offered in all barrel lengths and gauges.

In the later 1930s when Remington began offering factory Poly-Chokes, they milled them integral with the barrel as well.

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]