[DonVoigt]

Proofs and other markings on the receiver were quite likely removed.
The receiver could have been an early commercial receiver or a navy receiver. Neither had markings on the top or right side, but the Navy would have had some on the left as would most of the commercial pistols- but some commercial contracts may not have had any marking on the left. Most commercial pistols and the navy pistols did not have the serial number on the left chamber, neither did some other versions in the early years.

The breech block show severe pitting and any markings may or were likely removed in its re-finishing. The grips are nice looking Mauser inspected late P08 grips.

The numbering on the bottom lug, and marking on the bottom of the receiver- could be studied and the likely donor narrowed down a bit- it would take some time to sort out(for me), but maybe one of the "early luger" guys can narrow it down.

Basically it is just a "mongrel", built from parts and nicely re-finished.