Figure 3-57.--Projector of 7.62-mm ammunition showing maximum ordinate (H) of trajectory.
Figure 3-58.--Danger space at 1,000-yard range.
Figure 3-59.--Cone of dispersion, or cone of fire.
A number of shots fired automatically with a single
approximately two-thirds of the range from the weapon
pressure on the trigger is called a BURST OF FIRE. For
to the target (fig. 3-57).
normal ground targets, the number of rounds in a burst
DANGER SPACE is the area between the weapon
is usually from four to ten.
and the point of impact in which the bullet does not rise
When several bullets are fired from a rifle or
above the average height of a man (presumed to be 68
machine gun held in a fixed position, there is a slight
inches). At ranges up to 750 yards, a rifle bullet fired
variation in the trajectories. The causes of these
over level or uniformly sloping ground does not rise
differences are in the powder charge, the weight of the
above this height; therefore, for such ranges, the danger
bullet, atmospheric and wind conditions, and vibration
space is continuous. At ranges greater than 750 yards, a
of the weapon. These variations are known as
portion of the trajectory is above this height; therefore,
DISPERSION. The several dispersions, plotted in
the danger space is not continuous but exists for a
profile, form a cone with its apex to the muzzle of the
variable distance in front of the muzzle and in front of
weapon; this is known as the cone of dispersion, or the
cone of fire (fig. 3-59).
the point of impact. In the latter case, the danger space
begins again when the bullet comes within 68 inches of
The impact pattern of the cone of dispersion on a
the ground. The length of the two danger space zones is
vertical target (which would be oval in shape) is called
dependent upon the range, as shown in figure 3-58.
the VERTICAL SHOT PATTERN. (See fig. 3-60.) The
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