Approximately 43,000 of these "Fifth Model" Burnsides were manufactured c. 1863-1865 during the Civil War, per "Flayderman's Guide") 9th Edition, 9B-046. These "Fifth Model" Burnside carbines represent the completion of the evolution of General Ambrose Burnside's ingenious carbine design. They were the third most purchased breech loading carbine during the war, after only the Sharps and the Spencer. Features matching serial numbers on the frame and breech block, single letter inspection marks on various components, boxed script "NSP" and "RKW" inspection cartouches stamped on the left stock wrist, and "N.S.P." inspection initials ahead of the buttplate tang.