HGD,
In reply to your PM. Your shotgun was made in 1952 (D barrel date code), there are no choke markings on it so it likely had a factory polychoke but on a 28” barrel (the only length offered on the 820). The ordinance bomb stamps are not the ones used by Savage/Stevens, that style is what you see on Winchester, Ithaca and Remington shotguns from WWII. Stevens used a much smaller bomb with no distinction in the flames and a smaller P proof stamp. Most telling is the research carried out by Thomas Swearengen (The World’s Fighting Shotguns) and Bruce Canfield (Complete Guide to US Military Combat Shotguns) that states the US Military didn’t purchase any new shotguns for Korea. They didn’t need to as they had a huge surplus of WWII shotguns still on hand that they were busy selling off while fighting in Korea.

In my opinion your shotgun has been cut down and marked in the style of the WWII Stevens M520-30 (Model 520A) and M620 (Model 620A) shotguns but with inaccurate stamps in an attempt to deceive unsuspecting buyers. An argument could be made that this is an MWR gun from a base skeet range that was marked up by a unit armorer but it would still be a civilian purchased gun and not from a military contract and why did they go to the trouble of trying to mark it like the WWII Stevens contract gun. It’s a neat home defense gun that’s built like a tank with materials and workmanship no longer seen on modern shotguns but not a military gun.