And yes, they did indeed take just about any pump shotgun in inventory at the factory.

The story goes, the 520-30 was discontinued with the introduction of the 620 round back receiver, to compete with the more modern M12.

At the onset of war Uncle contracted with Stevens for all the left over 520-30 receivers laying around unsold at the factory.

I had an Ithaca skeet grade that was stamped FJA. The ONLY FJA stamped Ithaca shotgun I ever heard of. The gun was mint and real. The serials before and after than gun appear in the Ithaca sales records I have. That one does not. The "story" was that this gun was from the estate of a former President of Ithaca Gun. In fact, I bought it from a high end shotgun dealer located about 5 miles from the old Ithaca factory.

Buy the gun, not the story.

But there are some oddballs out there. The Remingtons posted here appear to me to be correct and original (except for recoil pads of course).

The "long barrel M97" was originally a riot gun. The barrel dated 1948 is a dead giveaway. However, M97 military riots in any kind of condition are extremely rare.