Designed by Gilbert Smith, the production of this carbine was almost entirely consumed by government contracts, with limited numbers going to the civilian market. Standard three sets of markings on the left side of the frame "MANUFACTURED BY / AM'N M'CH'N. WKS / SPRINGFIELD MASS", agents' names "ADDRESS / POULTNEY & TRIMBLE / BALTIMORE U.S.A." and "SMITH'S PATENT / JUNE 23, 1857". Dovetail front sight and folding leaf rear sight absent of yard markings. The left rear of the barrel at the breech is marked "L.F.R." Breech loading action with barrel release latch inside the trigger guard, freeing the barrel to pivot downward. Casehardened hammer and action with smooth straight grip walnut stock with a steel buttplate.