Haven't seen one - does it exist already?
Either way it's a damn cool sniper rifle.
It's essentially an AR-15 modified for accuracy and chambered for 7.62 NATO. The SEALs and apparantly the Israelis use it, and it can shoot at around .5 MOA, making it more accurate with the PSG-1.
Though, it can be a pain in the ass to maintain, but thankfully we don't have to worry about that in OFP. (Actually the only way it can beat the PSG-1 in terms of accuracy is if it's impeccably maintained
)
It's semi-auto, takes 20-round box mags, and can take a suppresor.
Link for specs and a pic:
http://world.guns.ru/sniper/sn13-e.htm