Well since you're buying the Valk anyways or have already, just keep in mind that the SG556 Mark II isn't in the market (or shouldn't be anymore for permanent???) anymore. So it's much more "rare", but then again "rare" doesn't matter if it isn't going to get you a faster kill. Anyways enjoy your gun, I personally have the SG556 Mark II and I like it. Cheers.