One of 1,000 Navy Model 1861 Signal Pistols manufactured at the U.S. Navy Yard in Washington, D.C. The frame halves are stamped with the number "4". The left side of the frame is stamped "U.S.O.Y.W/W.N.J/1864" indicating manufacture by the U.S. Ordnance Yard in Washington and inspection by W.N. Jeffers in 1864.