Luger 1917 DWM Again

Interestingly, many 1917 navy lugers were modified in just the way you describe (filing off rear sight and shortening the barrel) during the Weimar era by the German military. Are you sure this is not a Weimar rework and not a bubba-ized luger? See Jan Still's Weimar Lugers book for an example photograph. A similar modification process was applied to WW1 Broomhandles, too. This weekend, I observed a Broomhandle pistol that was shortened and rear site removed in a Navy holster. It was brought back in that condition from WW2 by a GI.