Back in the late 80's I bought a retired police 870 with the exact same stock set. Serial number had it manufactured in 1967. It also has a chrome lined chamber and 18" cylinder choke barrel. It had BPD deeply stamped in the butt stock. It was finished with a yellowed type of municipal varnish that had multiple coats and was chipping off badly. I finally decided to refinish the stock after it left me covered in varnish flakes after using it. To my surprise there was a beautiful piece of walnut under that varnish that still surprises me to this day whenever I look at it.