Jan Stills "Imperial Lugers" page 192, says that "Those for the 1904, 1906 and 1908 variations bear (sic)concentric ring bases, while SOME OF THOSE (emphasis added) for the 1916- and 1917 -dated Navy Lugers bear (sic) plain magazine bases".
The bidding could go crazy, if you have the matching Navy Luger.
Big Norm
