[mrerick]

The German military did not use .30 Luger (7.65mm) Lugers. Their military firearms were 9mm. When acquired by the military, they were acceptance marked.

The Swiss military did use this caliber.

I believe that there were some civilian agencies (like railway security Reichsbahn police services) that may have had these smaller caliber pistols. You would expect these to be marked as such.

A captured Luger would not normally come back from Germany with a "GERMANY" export mark.

Officers generally did not carry large pistols like Lugers, preferring pocket pistols like the M1914 Mauser and PP Walther.

By 1928, Very few private citizens in Weimar or Nazi Germany had licenses to lawfully possess handguns.

Given these things, the most likely original purchaser of this Luger would have been a commercial customer from a store in the USA or somewhere outside Germany. Any pistol encountered in the war theater was fair game for "capture", but one of those would probably have different markings.

Of course, knowing what was generally true is not the same as being able to factually state it's origin.

Many returning soldiers wanted a "war trophy", and any acquisition of a Luger pistol could fit that bill.