You need to find two weapons (one having a large ammo supply [like the chainsaw], and a good zombie killing weapon that your comfortable with using). Equipt the high ammo weapon in your primary weapon slot, and your preffered weapon in the secondary slot. Now, here's the trick... as the screen darkens when you push "start", tap the space bar to swap weapons. You should be holding your secondary weapon, and it should have as much ammo as your primary weapon. For instance, if you had a chansaw as your primary (which has a 50 round clip) and a revolver as your secondary (which has a six round clip), your revolver will them have 50 rounds of ammo in it. Use it wisely! As soon as the 50 bullets are gone, you'll go back to using the normal amount of ammo in your gun.
