The German directive for modifying the French M1886 is very specific. This is not to say the armorers whom did the work always followed such orders to the letter. However, the French themselves modified and/or shortened a number of M1886 bayonets during WW1 and in the interwar years...often to salvage a bayonet having a damaged blade which in all other respects was serviceable. A copy of the German directive can be seen on page 211 of George Wheeler's book Seitengewehr A History of the German Bayonet 1919-1945. It appears from the sketch the overall length of the bayonet, from the end of the pommel to blade tip, is optimally 460mm. Other dimensions are also outlined, like the angle of the new blade tip, and scabbard modification as well.