Patented in 1875, the Metcalfe device was invented by Ordnance officer Henry Metcalfe, consisting of a steel mounting bracket installed on the rifle and interchangeable wooden cartridge blocks. The blocks were to be issued pre-loaded and carried on the belt, replacing the cartridge boxes of the day. While the system never took off, echoes of it can be seen in the practice of issuing ammunition in pre-loaded "stripper clips" starting in the 20th century. Blade front and folding ladder rear sights, with a high-arch breechblock, 2-click tumbler, and an 1873-marked lock. Smooth straight-wrist stock, with the Metcalfe bar on the right side, and a "US" marked buttplate. One cartridge block is included.

Very good as an assembled example, with a mixed gray patina on the barrel and ramrod, strong blue on the bands, Metcalfe bar and trigger guard, and darkened casehardening on the lock and breechblock. Mild pitting is present around the breech and forearm tip, and the mounting hardware on the block is a bit loose. The wood is fair, with some cracking around the lock and tang, scattered dents, and some mild chipping. Mechanically very good. A solid representative example of this unique variant of the trapdoor Springfield rifle collecting field with all being assembled from parts!