Um, not an exploit. Its a feature, not a bug. I've never used it in Crucible, but I'll be very pissed if they remove it from PVE (I'm not much of a sniper anyway). This wouldn't be a problem if nerf/buffs only affected the side of the game that was being ruined by the item needing the nerf/buff. Time to separate PVP/PVE now! The Special Ammo Nerf wasn't enough. It should have been closer to the way Heavy Ammo behaves.