You have an honest police Luger that was, at some point in time, repaired by an official facility as indicated by the mark (HZaJt18) on the sear bar, likely indicating replacement. The barrel was replaced, maybe at the same time as it has the bore diameter marking but isn't serial numbered to the gun. Between 1928 & 1934, Lugers that were rebarreled for police use were marked on the right side of the new barrel with "PTV" and an eagle. In 1934 that changed to "PT" and the eagle as on your Luger. The new barrel on yours was obviously installed after 1942.
IMO you've done well for your first - there WILL be more - Luger.
