Well, I did a little more reading, I think I have an original riot gun, while the barrel blueing is less worn than the reciever, the barrel is stamped "41" underneath at the chamber end, and the 922xxx serial number seems correct. Both barrel and reciever have a P over W stamp in a circle, so the barrel seems original to the gun, I did not know any of these guns used a full choke and a longer 28 inch barrel.. This shotgun also has a stock swivel, but then also a rather home made looking upper swivel that I should take a picture of and post to see if it is what should be on the gun...