FM 3-22.68 HEADQUARTERS FM 3-22.68 DEPARTMENT OF THE ARMY CREW-SERVED MACHINE GUNS, 5.56-mm AND 7.62-mm
5-3. CONE OF FIRE When several rounds are fired in a burst from any machine gun, each round takes a slightly different trajectory. The pattern these rounds form on the way to the target is called a cone of fire (Figure 5-2, page 5-2). This pattern is caused primarily by vibration of the machine gun and variations in ammunition and atmospheric conditions.
FM 3-22.68 5-2 5-4. BEATEN ZONE The beaten zone (Figure 5-2) is the elliptical pattern formed by the rounds striking the ground or the target. The size and shape of the beaten zone changes when the range to the target changes or when the machine gun is fired on different types of terrain. On uniformly sloping or level terrain, the beaten zone is long and narrow. As the range to the target increases, the beaten zone becomes shorter and wider. When fire is delivered on terrain sloping down and away from the machine gun, the beaten zone becomes longer. When fire is delivered on rising terrain, the beaten zone becomes shorter. The terrain has little effect on the width of the beaten zone.
The same can be said for the Bradley Fighting Vehicle as with the LAV's. They have a secure mount and this helps limit the dispersion of the rounds. But no matter how secure the mount is vibration will effect the dispersion of the rounds.
