Hello Joe,
I have checked in the Mauser Ledger and I have found your pistol that is nicely displayed together with all the others (few) 5" Parabellum produced. Actually all the 5" production is tracked in the production book. Believe me your pistol is rare!
I have the production day of your pistol plus other info.
If you are interested in the certification please contact me:
mauser.archive@gmail.com
Cheers,
Mauro