That means you have hit detection lag. I have to shoot 20 bullets to get 3 hitmarkers with any machine gun. Yesterday I decided to go ahead and remove the map packs, and somehow most of the hit detection lag is gone. I knew this would work since it did when I lived on a slow internet connection on MW2 I would have lag with the map packs but not without them. Except now I'm on the best connection available and on Black Ops. This hit detection issue only happens on Treyarch games. I think I was the host on one of the games I played yesterday since I got 2 kills on my screen, but they only appeared in the killfeed 5 seconds later. Or maybe I wasn't host but he was someone where I didn't have that much lag. Do they actually effect it? I store mine on a flash drive so that it only needs to be in use whenever I'm using a map pack map.