[mrerick]

Looks like a Luger that was used in police service in Berlin. The "1921" date on the chamber is the production year, and this one looks like it did not receive the modified sear safety or magazine safety.

The serial number stamped on the frame looks odd. I can't tell if it's been renumbered. It's certainly something that needs looking into.

I would expect Weimar proof and acceptance marks on a 1921 pistol's receiver. Have these been removed, or were they ever there?

Shooting an all matching gun won't affect it's value. Shooting the gun and breaking a numbered part will affect it's value 35-50%. Your experience may vary. If you buy it, it will be yours to do with what you want. I don't shoot mine, but for every one shot and broken, mine go up in value a little bit since there are fewer collectible guns.

I can't answer your question about value because I'm unsure if it's completely righteous.