Wubz4days, I once actually played a version of this game on another site in which the marathon achievements were extended to heck and back, and you really did have to shoot the KAR98K 98,000 times. Boy am I glad you don't have to do that here.
Well, so far I've reached day 28, with no zombies having done any damage to the barricade. So far, so good. The Sprinfield and the Remington were super awesome, while the fast firing guns did very well as alternate weapons when combined with the Rage mode.