INFANTRY: Probably not the hardest, but still definitely pretty hard: the AC-X11 without HVA, with a suppressor on it. I actually do use this loadout from time to time as LA and it's really not so bad, but pretty much ANY other automatic gun would perform better XD Number one because this is the hardest automatic loadout to use and everyone uses automatics anyway, so it seems the most pertinent to the topic. Probably the most difficult would be Pump Action Slugs. Maybe they will be more viable after the Nanoweave changes buffing headshots, but for now, PA Slugs is probably the ultimate hardmode. Honorable mention, the iron sights/reflex BAR with a suppressor on it.