I think yours is a copy. The two most common makers were L.F.C (Landers Frary & Clark), and a French maker, Au Lion. The L.F.C knives were marked 1918 on the handle and L.F.C. just below the date. The Au Lion knives were just marked 1918 on the handle, with Au Lion over a lion on the blade. The blade should be 6 3/4" long. Reproductions of the knives are still being made to this day. It is quite common to find copies that have been artificially aged, and attempted to be sold as originals. Your handle looks like a lower quality modern casting, probably from somewhere overseas. The numbers arent as bold and as crisp, they are kind of rough. There also is no patina on your knife, and the color of the blade doesnt even look like steel (maybe just looks like that in the picture). The original 1918 L.F.C metal scabbards for the knife are usually worth as much as the knife itself.