Rifle Fire and Its Effect
Rifle and automatic rifle fire and its effect comprise the second step in technique of fire training. A knowledge of what the BB does while it is in flight and an understanding of the effects of fire on the enemy can assist the rifleman in obtaining maximum effectiveness.
Trajectory is the path of a BB in its flight through the air. The trajectory is almost flat at short ranges, but as range increases, the height of the trajectory increases.
The space between the rifle and the target, in which the trajectory does not rise above the height of an average man (68 inches), is called the danger space. A BB fired from the rifle at ground level (prone) at a target located at relatively short range gives continuous danger space, providing the ground is level or slopes uniformly. At greater ranges, only parts of the space between the rifle and the target are danger space because the trajectory of the BB rises above the head of a man of average height. When the trajectory of the BB does rise above the head of an average man, this is called dead space.
Cone of Fire
Each BB fired from a rifle at the same target follows a slightly different path or trajectory through the air. The small differences in trajectories are caused by slight variations in aiming, holding, trigger squeeze, wind, or atmosphere. As the BBs leave the muzzle of a weapon, their trajectories form a cone shaped pattern known as the cone of fire.
The cone of fire striking a horizontal target forms a beaten zone which is long and narrow in shape. Beaten zones on horizontal targets vary in length. As range increases, the length of the beaten zone decreases. The slope of the ground affects the size and shape of the beaten zone. Rising ground shortens the beaten zone; ground sloping downward at an angle less than the curve of the trajectories lengthens the beaten zone. Ground that falls off at an angle greater than the fall of the BBs will not be hit and is said to be in defilade.
Classes of Fire
Rifle fire is classified both with respect to the target (direction) and with respect to the ground.
Fire With Respect to the Target.
- Frontal Fires
Fires delivered perpendicular to the front of a target.
- Flanking Fires
Fires delivered against the flank of a target.
- Enfilade Fire
Fire delivered so that the long axis of the beaten zone coincides or nearly coincides with the long axis of the target. Enfilade fire may be either flanking or frontal.
Effect of Rifle Fire
The best effects from rifle fire are obtained when the squad is close to the enemy. The squad should use cover and concealment offered by terrain and take advantage of the supporting fires of machine guns, mortars, and artillery to advance as near to the enemy as possible before opening fire. Normally, it should not open fire at ranges greater than the maximum effective range of the rifle.
The area in which the enemy is located can usually be determined by the sound of his firing. Troops may distribute continuous fire in width and depth to cover the entire area, causing the enemy to keep his head down and making his fire ineffective.
Rates of Fire
The rates of fire of squad weapons combine to form the firepower of the squad. Weapons employment and squad firepower are not determined by how fast Marines can fire their weapons but how fast they can fire accurately. The squad or fire team leader must be able to control the rate and effect of his men's fire, otherwise, ammunition is wasted.
- Average Rate
This term refers to the average rate of aimed fire a Marine can deliver with a semiautomatic rifle.
- Sustained Rate
This term applies to automatic rifles and machine guns. It is the actual rate of well-directed fire a weapon can deliver for an indefinite length of time without causing a stoppage or malfunction due to overheating.
- Rapid Rate
This term applies to automatic rifles and machine guns. It is the maximum amount of controlled fire which can be delivered on target for a short period of time (usually not more than two minutes) without causing a stoppage or malfunction due to overheating.