Park & 14 finned bbl = Military gun.
That said, there are actually no specific features which make a Reising 'commercial' vs. 'military', as they were never issued that way. However, typical differentiators include:
Commercial: 21 bbl fins, blued finish, a standard screw-type takedown screw
Military: 14 bbl fins, parked finish, thumb-nut takedown screw
That said, IIRC there were later 'commercial' guns manufactured with the blue finish but having the lower bbl fin count and thumb-nuttakedown screw of the military versions.
FWIW ...
Howard