Winchester M12 WWII rebuild?

What are the chances? A local shop has a Winchester Model 12, which is advertised as "possibly" being a WWII rebuild. According to the serial number, the receiver was made in 1917. The barrel appears to be an original riot barrel, with a flaming bomb over the Winchester proof, and it is marked "42" under the barrel, and is also marked cyl. The barrel has been parkerized, along with the magazine tube. The receiver has a nice patina, but there are no U.S. markings on the receiver or stock. Looks to me to be put together by someone wanting to pass this off as a rebuild, but is it possible? Sorry, I don't have any pics. Input is greatly appreciated.

The fact that it has a blued receiver in poor condition and a parkerized barrel leads me to believe it's a "put together". An arsenal rebuilt gun would have been fully parkerized.

My rebuilt model 12 is completely parked. And the rcvr is marked US along with TE arsenal stamp on the stock.