how about nexon make it belong in a special barret only mode, like instagib from the UT series, boom, and you're done, and everyone gets it.
if not, then they can make the gun sway A LOT in scope mode, like America's Army's M82 (a gun as heavy as the barret is very hard to hold still), that gun was impossible to use except in prone supported, and give it similar recoil (i.e. 1 shot and you're looking at the ceiling)