If only I had the money and the class III license:
Vltor - Projects - PKM BeltFed
Be sure to check out the two demo videos near the top of the page.
I wonder how long it will be before they have the semi-auto receiver ready for sale with it. This, the Dragunov (and its variants, see below), and the SV-98 are the only guns other than our Mosins that take 7.62x54R, that I'm aware of.
Oh, and even though it's an airsoft page, there's a really informative page if you're interested in Druganov's:
Unconventional Airsoft 
