If the price is right, this would make a great "working collectible"!
I had an LC Smith 16 guage "Featherweight Field" grade with their special high rib that had purchase papers from Smith to Syracuse Army Depot in 1942. Hard to imagine this gun being used for training and easy to imagine that it got into the inventory of some O-Club and was used for recreation.
I've also seen Savage 220s, Win 37s, etc that were unlikely to have been used for training. More likely recreation and/or rat control.... (These were guns I saw MANY years ago before anybody thought a "martially marked" single shot would have collector value. Very unlikely to have been fakes).
Uncle Sugar just bought up about all the bigger guage shotguns available in 1942 and then tried to figure out what to use them for. Some were used for "military" purposes. Some not.
