As someone with an m107 and a couple magazines in their pack, I feel I can safely say that these weapons really don't need to be in the game. In the context of a mil-sim with zombies and survial elements, an anti-material rifle is obscenely inefficient. As the OP stated, these things are damn heavy, running around with them for days and weeks across the countryside really isn't feasable. In the context of a survival FPS anti-material rifles are entirely too powerful. Hitting hard enough to to kill at any point on the body without any real drawbacks to its use. The other sniper rifles require actual precision for 1-hit kills where the AS50 or M107 will kill a player three times over just for making contact. And let's face it, for every thosand kills from these rifles, only a couple vehicles are being disabled. Keep sniping fun and rewarding, remove these or make them soak up both the primary weapon and backpack slot so using one is an actually meaningful decision.