Is this M1D Authentic?

[JGaynor]

My M1D's Barrel is marked as follows:
Barrel – Under rear hand guard app. 3.5 inches in front of receiver ring (12 o’clock)
Drawing Number D7312555 A178B

Symbol - Ordnance Escutcheon (crossed cannons encircled by belt) M M


Barrel Date: at 3 o’clock viewed from chamber (viewable with bolt retracted)

S-A – 10-52

Letter “P” lying on its side

My understanding is that the M1D Barrel Assembly (D7312555 bbl w/ scope base) was marked in the majority of cases at 12 O'clock under the rear handguard.

Regards,

Jim