That 404 would be the serial number. I think from the pictures that your gun is the lower quality gun with just the "Greener" cross-bolt. Open the gun and if it doesn't have a lug on the bottom of the barrels like the gun I pictured it is.
From the pictures your gun appears to be badly off-face. There is not much of an established market for these guns from companies that only lasted a couple of years. They are really only of interest to us nut cases who want one of every kind of double manufactured in North America. I can't imagine the gun you picture being worth more then a couple hundred dollars, probably a lot less for a quick sale.
