You might wanna read the definition of a nerf. We got 310 from the mission. Whether it was a bug or not, a nerf by definition is the lessening or weakening of a weapon in gaming terms. Yes, we can always infuse one back to 310. But for all intents and purposes, it was nerfed. Just as infusing is a way of buffing a weapon. Imho, with the weapon dropping at 290, they might as well make it a bounty. Who would waste time on a 290 sniper? Yes, it's a guaranteed, but the value of acquiring has dropped.