I personally don't think anything should be OSK without drawbacks. Shotgun is OSK at short range, fusion has a charge and snipers require headshots. So Final Round Sniper kills to body should be nerfed as they are too easy. However I'm not sure how to nerf it, as it does add interesting weapon variation. Maybe make Final Round apply to the final shot overall just for snipers? That keeps the variation, still gives it value but also reduces how often it can be used.