[DonVoigt]

I find it tough to square the "rules out the window" conjecture when the 1920 DWM Commercials, i.e. the alphabet commercials- are inspected and proofed without notable exception.

Dick,
what were the secret codes in 1925?

Lugers rebuilt and proved in Suhl post WWI have their own similar but different Crown/N proof; If this time was such a free for all- why were they marked at all?

The simplest and probably most accurate assumption is that the proof marking was removed from the OP luger during subsequent re-finishing. JMHO.