An original antique U.S. Model 1816 Springfield bayonet with antique patina. The blade is 16" long with a groove from the tip to mid length. Overall length is 19", with a 3" long socket with zig zag T slot. The socket is marked 58. The blade is marked US over what appears to be JB but the bottom marking is very difficult to read. The base of the blade is stamped L.