I would also guess 1942. I have a 20,xxx range gun marked with the ordnance bomb proof as yours is. I also have a 39,xxx range Commando with a "P" proof and punch mark on the upper left frame and "P" proofs on the rear of the cylinder and under side of the barrel and a 47,xxx range Commando with no Govt. marks, only the Colt factory markings. These are interesting revolvers and most were used by production plant guards and civilian law enforcement in the same manner as S&W Victory revolvers. I believe that even though the ser # ranges go just above 50,xxx, just less than 50,000 were produced, making them harder to find than Victory models. Colt also made a factory 2in barrel variant and some were also stamped "GHD," for Col. Guy H Drewery, the commanding officer of the Hartford Ordnance District. Does yours have any other markings ?
