Snipers themselves are not the problem (neither were fusions or shotguns). It's the seemingly unlimited special ammo available on the map. Cut out ammo crates completely and give every guardian 1 clip of special ammo and no more as well as disable ammo regen in PvP. In elimination (round based) game types give each guardian 2 special ammo bullets (enough for two potential kills in sidearms) per round and the problem is solved. It will become true special use and not be everyone's primary weapon like it is now.