Ammo boxes are frequently found in gun-oriented games. In many games, the placement of an ammo box could spell the difference between victory and defeat. No virtual soldier can go into battle without certainty that there will be plentiful boxes of ammunition waiting for him in the battle field.
While no soul alive can deny the usefulness or the necessity of the ammo box, it is in the area of plausibility that they raise eyebrows. For games that strive for realism, having large collections of ammunition laying in the middle of a battlefield may break the illusion. Also, the virtual soldiers never seem to question why the guns that their enemy use contain ammunition that is identical to the gun that he is using. They also never question why they do not have to bend over and pick up the ammunition, but instead simply stand over it, and all of the bullets, cartridges, etc. simply float into the weapon at hand.