That all depends on whether there is a registered, live gun out there. If someone has a live gun, then the drum would be worth alot to them. Perhaps several Thousand dolllars.
I would take this over to the machinegun sites, (
www.subguns.com and
www.sturmgewehr.com) and post it on their forums. If there is a gun owner out there this may smoke him out. The alternative is to donate it to the Air Force Museum in Dayton, Ohio or the Smithsonian Air and Space Museum and take a hefty tax write-off