Gwyn & Campbell manufactured around 8,200 of the Type I and Type II carbines in 1863 and 1864, and the carbines were primarily issued to a variety of Midwestern units during the Civil War. "UNION/RIFLE" marked on right of frame, lock marked "GWYN & CAMPBELL" in an arch over partly visible "PATENT/1862/HAMILTON. O", boxed script "WHR" cartouche stamped on the left wrist, and small "WHR" inspection initials on top ahead of the buttplate tang. Matching visible serial numbers on the bottom of the barrel, frame, breech block and lever.