1914 Navy Lugers (Dated 1918)...?

Need some help...noticed two (2) 1914 Navies for sale on gun-sites that say the 1914 Navy luger is 1918 chamber dated.


My question is : Were 1918 chamber dated, 1914-Navies made ?


C. Kenyon (Lugers At Random) on page 156 says 1914-1918 dates are possible.


J. Walter (The Luger Story) on page 143 says chamber dates of 1916 and 1917 are known, but with surving inventory info. reveal that deliveries were being made at the end of the war.


M. Reese (revised edition Luger Tips) on page 46 says chamber dates from 1914-1918, with few having a 1914 or 1915 chamber date.


J. Still (imperial Lugers) on page 159 only lists 1916 and 1917 chamber dates in his Table 6. On page 164 Still states "the 1914 Variation Navy Lugers have 1916 and 1917 dated chambers and short frames...".


Needless to say, I cannot figure this out. I also do not have the Navy Luger book by Gortz & Walter to see what that says...