S165U, Models 1855-1865, to include all those experimental rifles made from those muskets and the Allin trapdoor rifles as well, all the way up to 1878 models in 50-70 calibers. Originally made for the Civil War, plenty of them were left over for use until finally the government went over to the 45-70 caliber trapdoor rifles and thus a new bayonet had to be made to fit them. The US mark on this specimen is almost worn off but visible, with a dot above it and S stamped beneath it. In very good used condition, all functional, guaranteed to fit your relevant gun. Only minor brown patina, no pitting. In full length, never shortened, or sharpened in any way. Overall length 21", all original, ship weight is 3 pounds.