I have searched high and low for a recoil spring for an SVD that I bought that was missing one. Tempted to get some made at this point but not sure if there's a market for it or not.
Doubt that its actually contraband, most of the time (read 99%) these were all papered but the papers have been lost with time. I use a local attorney who specializes in this kind of stuff. Would be worth pursuing before taking other alternative steps.