ok.. this game isnt entirely about realism, it's a game, not a simulation, and even if it was that dedicated to realism, and squads of seals and spetznas were crawling chernarus..... who cares, it's simply not balanced to add silenced sniper rifles, if your argument is "ooh i cant help my friends shoot zombies" then get a different bloody gun or use the sniper rifle properly- from a distance, it's not the snipers purpose to take out zombies- atleast from close range, for the most part it's to shoot other players if you want to help your friends, get a gun made to help them with, or just friking camp at a safe spot like any smart sniper, and even then if you're stupid enough to give away your position to shoot zombies, you're going to die anyway. tl;dr, get a silenced assault rifle.