This experimental repeating conversion of a Trapdoor Springfield was most likely made by Augustine Sheridan Jones, of the Dakota Territory in the 1880s. We know he submitted a different type of magazine-fed Trapdoor to the US military’s 1882 repeating rifle trials, and this rifle also came out of South Dakota.

At any rate, what the designer did was to, remarkably, figure out a functional way to add a tube magazine to the Trapdoor system. It even has a magazine cutoff feature, allowing it to be run as a single shot rifle with the magazine held in reserve, or as a repeater…