Machine Gun Employment: Theory and Tactics

This short article is taken from our new Small Unit Machine Gun Employment book. The article discusses a selection of concepts and techniques that are critical to effective machine gun employment We welcome your reactions, comments and ideas on our Facebook page and if you like the article, click below to check out the book on Amazon.

Machine Gun Employment: Theory and Tactics

Our latest book goes into detail on a wide range of topics relating to machine gun theory and various tactics and techniques for using machine guns in combat. This article takes a selection of short paragraphs on several key concepts and useful tactics that are critical for effective machine gun employment. The full book goes into more detail on each of these topics and shows how they relate to each other in the bigger picture.

Grazing Fire

If you point an M240B machine gun horizontally at a target that is less than 600 meters away, the bullet will travel in a fairly straight trajectory and strike the target. However, the bullet is actually not flying in a straight line (we will discuss this more in coming sections) but is rather traveling in an arc. When you fire a bullet from the machine gun it will obviously not continue on forever but will instead begin to lose energy and the force of gravity will cause the bullet to drop to ground level. If you fire an M240B medium machinegun roughly horizontal with the ground, the bullet will travel about 600 meters before hitting the ground. This is called “grazing fire” because the bullet is essentially grazing along the surface of the earth. Grazing fire travels in a generally straight line, one meter or less off the ground. In the example below, it would hit any of the four enemy troopers on the left since they are within 600 meters. However, the bullet will hit the ground before it reaches the enemy trooper standing on the far right side of the diagram. The maximum effective range of the M240B machine gun is 1800 meters, so how can we engage the enemy trooper on the far right?

Plunging Fire and The Beaten Zone

To understand how to engage targets that are farther away than 600 meters we must first understand more about bullet trajectory. As already mentioned, when you fire any bullet from a gun it does not travel in a straight line but is rather subject to the forces of gravity and drag, just as when you throw a ball through the air. When you fire a bullet it travels upward along an arc-shaped trajectory until it reaches the highest point (or maximum ordinate) around 2/3 of the way along the trajectory. The bullet then begins to drop downward until it impacts the ground.

Machine guns fire bullets in a “cone of fire.” If you fire a burst of bullets at a paper target in front of you, the bullets will spread out on the target forming a cone shape from the muzzle of your machine gun. The further away these bullets get from the gun, the wider the cone will be since the bullets continue to spread apart as they fly. With this in mind, consider the diagram below. As you fire a burst, the cone of fire begins to spread as it travels along the arc-shaped trajectory discussed in the last section. Therefore, when the bullets impact the ground they do not impact all at the same point but rather in an oval-shaped area on the ground called the “beaten zone.”

We now return to the diagram we used to discuss grazing fire with the same five enemy troopers spread out at different ranges. If you recall, when employing grazing fire the same burst of fire could hit any of the four enemy troopers on the left because they were all within 600m. However, we were unable to engage the trooper on the far right with grazing fire because a bullet from an M240B will only travel along the ground for 600m before striking the earth. However, if we point the weapon higher and raise the trajectory of the bullets, the burst will fly farther and be able to hit the enemy trooper on the far right. The bullets will fall on the enemy trooper in a downward angle and that is why we call this type of fire plunging fire.  However, note that because we raised the trajectory of the bullets, they will now only be able to hit the enemy on the far right and will pass harmlessly over the heads of the other four enemies to the left. So while grazing fire could have potentially hit any of the four troopers to the left, in this example of plunging fire, only enemy troops standing inside the beaten zone can get hit by the machine gun bullets. NOTE: The diagrams are not to scale and do not reflect actual ballistics. They are exaggerated for explanation purposes only.

Enfilade Fire

Enfilade fire is when the trajectory of fire (grazing fire or the beaten zone) is aligned and parallel with the long axis of the enemy formation. This is the most lethal orientation of fire as it relates to the enemy’s formation. This is because as a bullet passes through the formation, it will have a greater chance of hitting someone if the entire element is in a line. A single bullet can also pass through two people. Enfilade fire also makes the shooter’s job easier since he/she can target the entire formation without having to traverse the weapon to the left or right. The image below shows an example of enfilade fire.

While more linear formations are particularly vulnerable to enfilade fire that passes through their long axis, they are less vulnerable to fire that is perpendicular to the long axis for several reasons. The illustration below gives an example of this. Each incoming bullet has less chances of hitting and if it does hit someone, it will pass through the formation and not hit anyone else. It is also more difficult for the gun to engage multiple targets since it will have to traverse left and right to engage each target. For this reason, machine guns should always try to achieve enfilade fire on the enemy formation.

Angles of Fire and the “Tactical-L”

The term tactical-L describes a situation where the enemy is taking fire from two perpendicular (90-degree) directions. This makes it difficult for the enemy to take cover since taking cover from one direction of fire will generally expose him to the other direction of fire. In the example below, you have two guns firing from a tactical-L on three enemy troops taking cover behind a large boulder. The boulder is protecting them from fire to their front (from the gun marked in blue) but the fire coming in from the flank (the gun marked in green) is about to cut down their formation. If the enemy troops repositioned to take cover from the green gun, the blue gun would then have a clear field of fire. Therefore, achieving a tactical-L with your fire makes it difficult for the enemy to take cover. Even if the enemy is dug in, with protection from every angle, the tactical-L still offers an advantage since the enemy will have to distribute their return fire in two different directions. It is also important to note that it is not critical to achieve a perfect “L” or precise 90-degree angle for the concept of the tactical-L to prove effective. If you widen the angle between your guns, even slightly, you are taking advantage of the tactical-L concept.

Sequential Fire

In some tactical situations, the best way to employ your machine guns is to engage with all guns simultaneously to mass maximum effective fire and overwhelm the enemy as quickly as possible. However, in other cases it can be more advantageous to open fire with individual guns in sequence. This means having one gun open fire first but waiting before opening fire with the second gun. The main reason for employing sequential fire is because it keeps the enemy off balance by forcing him to react to a changing situation and multiple threats. When you open fire with the first gun, the enemy will react accordingly and begin to maneuver and make decisions focused primarily on that single gun. When the second gun opens fire it will likely take the enemy by surprise and force him to rapidly adjust his plans, position and maneuvers accordingly. It is also possible to use the first gun to force the enemy into taking actions that will leave him more vulnerable to the second gun. In the example below, the enemy starts off moving in a file (1) but when the green gun opens fire, the enemy comes on-line behind a berm to take cover from the green gun’s fire (2). However, while protecting themselves from the green gun they unknowingly line up to expose themselves to enfilade fire from the blue gun, as well as a “tactical-L” between both guns. If both guns opened fire at the same time this sequential trap would not work. Note that in the diagram below no cover/concealment is shown for demonstration purposes.

We hope you found the short article useful and once again we welcome your reactions, comments or suggestions on our Facebook page where we frequently hold constructive discussions on tactics with people from various tactical backgrounds and experience levels. Also, click below if you would like to check out the full book on Amazon.