Pete,
I believe it has been mentioned in some the previous discussions on full automatic designs. Try some searches on Full Auto or similar keywords. If anyone knows, it might be our dear friend Albert Beliard. How about it Albert?
Pete, If I am not mistaken, haven't you corresponded with Dr. Regnier before on other matters (Swiss Lugers and accessories)?
Why not drop him an email line and request that he photograph this unique Luger and it's mechanism so that the photos can be posted for posterity here on the Lugerforum... mention of course that all photography and history would be credited to his generosity...and include a link to his website.
Perhaps he will honor us with this effort.