Sounds like it was salvaged from one of those "boating accidents."Rescued an old Remington 31 (predecessor of the 870 series) from a pawn shop about 20 years ago. Bore was heavily fouled, and after removing that I found rust in the bore as well as the magazine tube. Took a 1/2" dowel rod, cut a slot about 2" into one end, slipped in a double-layer strip of 400-grit wet-or-dry, chucked it into a drill and slicked up the bore and mag tube. Replaced the magazine spring, badly rusted. Exterior surfaces cleaned up nicely with 0000-grade steel wool, very little pitting and a nice blue finish. Good cleaning and light lube.