Welcome to the forums from the Wiregrass! Well, if there is no letter in front of those numbers, it is from the late 1930's. Not sure what you mean about military issue as there were no US military guns being made in that time frame. We were making .38 S&W cartridge guns for the UK in 5" barrels (a few were 6" and a few were 4"). You'll have to post some pictures of the gun showing any markings stamped on it.