Rolla Heikes with his Remington Autoloading Gun about 1905 courtesy of Chris Lien





The Baker SBT with a ventilated rib was introduced in 1909.
Dave posted previously that the 1909 Remington catalog listed a matted rib or a ventilated rib ($16) on the autoloading gun. The No. 525 Stevens Repeater with a "Hollow Matted Rib" was introduced in 1911.