Lets be honest a gun that can one shot a player through an overshield with a body shot from the opposite side of the map is not balanced. The gun is so easy to hit with that you almost never see someone miss from across the map. It is far easier to get full map shots with sleeper than a sniper and sleeper hits harder. The gun doesn't need to be nerfed in all modes, but it definitely needs a nerf in gambit. You can tell people to "get good" all you want, but just because a person can still win through skill, doesn't mean that it was a fair fight and that sleeper is balanced. It just means that they were able to overcome a disadvantage. We had the same problem in Destiny 1 with the hand cannon Thorn in Trials. Every trials team you would see was 3 people all running Thorn. It made the game boring and once they nerfed hand cannons, you saw a lot more diversity and more interesting gameplay.