My guess is it's a Lunchbox Special. An employee during the 40's-50's scrounged a bunch of old parts in the warehouse/attic/cellar and created a work of art, reminiscent of the stuff the factory was turning out when he started working there. Number not in keeping with the receiver ring stamp and configuration of the receiver? Pick a number out of thin air and get your buddy in final inspection to stamp it on for you.
Without solid provenance, that wild guess is as good as any other.
At the factories I worked in back in the 70's-80's, we called them "Government Jobs"- when guys threw stuff together for themselves, or completed hobby jobs on the company's time. I would be really surprised to learn none of that ever happened at Savage.
At K-D Tools when I supervised the torque wrench assembly department, my guys dog-robbed the parts bins and made wrenches for themselves. You would see Snap-On heads attached to Craftsman barrels with Blue Point handles. (We made torque wrenches for a bunch of different companies.) Buddies of mine who worked at the Harley-Davidson plant (the engines were built there in York, PA) showed up with all kinds of bastard parts on their bikes. It's what guys did when no one was watching- for money, devilry, or sheer boredom.
