Machine Gun Employment Flashcards Preview

Exam III > Machine Gun Employment > Flashcards

Flashcards in Machine Gun Employment Deck (72):

Define Trajectory

The arching flight path of the round from the muzzle of the
weapon to the target.


Define Ordinate

Elevation of the flight path of the round above the line of


Define Maximum Ordinate

The maximum elevation of that round above the line of sight
along its flight path. This distance is reached at 2/3 the
distance to the target.


Define Cone of Fire

Each round fired from a machine gun travels a different
path. Vibration, tolerances of the ammunition and weapon,
and shooter positions all play a role in these differences.
The pattern of these rounds is called the cone of fire


For an
M240B the cone of fire is always

2 mils wide


Define Beaten Zone

The beaten zone is defined as the elliptical pattern formed
by the impact of the rounds. Again, because the cone of
fire is always 2 mils wide, the beaten zone as well is two
mils wide out to the maximum effective range of the gun.
There are, however, differences in the length based on the
Uniform terrain and Rising terrain and Falling terrain


Uniform terrain is

At short ranges the beaten zone will be
longer because of the initial trajectory and narrow because
of the relatively short distance the bullet travels before it
strikes the ground. As range increases, the beaten zone
decreases in length because the bullets will be falling at a
steeper angle and increases in width as the rotation of the
bullet further affects dispersion.


Rising terrain is

Terrain rising in the path of the cone of fire
has the effect of abruptly stopping the rounds and creates a
small beaten zone which nearly duplicates the pattern of
the cone of fire on steeply rising terrain.


Falling terrain is

When the terrain falls away before the gun, the
beaten zone becomes longer and depending on the range, either
long and narrow or long and wide.


Machinegun in relation to the ground is

Dead Space

Danger Space

Plunging Fire

Grazing Fire


Dead Space is

Dead space occurs anytime the target (or
enemy) drops below the line of aim or line of sight. This is
largely a product of terrain. Streams, ravines, draws and
other features may cause dead space.


Danger Space is

When firing over terrain, any space up to
1.8 m above the deck (the height of an average man) is
considered danger space; that is, within the effects of the


Plunging Fire is

Plunging fire is defined where the danger
space is confined to the beaten zone. Plunging fire is
obtained when firing from high ground to low ground or low
ground to high ground and when using long range fires; an
example of this when a gunner engages a target on a street
from the third deck. The effects of the rounds are limited to
the beaten zone where those rounds are hitting the deck.


Grazing Fire is

Defines fire where the center of the cone of
fire does not rise more than one meter off the deck. This is
the most effective type of fire we can employ, and we will
always seek a position where we can bring the greatest
amount of grazing fire upon the enemy.


Machinegun in Relation to the Target is

Flanking Fire

Fontal Fire

Oblique Fire

Enfilade Fire


Flanking Fire is

Fires delivered on the flank of a target,
when the target is oriented 90 or more degrees away from
the firing unit.


Fontal Fire is

Fire delivered on the front of a target, when
the target is oriented on the firing unit.


Oblique Fire is

Fire delivered on the oblique of a target,
when the target is oriented between 0 and 90 degrees to the
firing unit.


Enfilade Fire is

The long axis of the beaten zone coincides
with or nearly coincides with the long axis of the target. This
class of fire is either Frontal or Flanking and is the most
desirable class of fire with respect to the target, because it
maximizes the use of the beaten zone.


Machinegun in Respect to the Gun is

Traversing and Searching
Swinging Traverse
Free Gun


Fixed is

Fire delivered on a point target. Little or no manipulation of the gun is required to obtain and maintain effect on target.


Traversing is

fire delivered against a wide target requiring changes in direction. The beaten zones of each successive burst should be adjacent to each other if not overlapping (may be produced from either a tripod or bipod).


Searching is

Fire delivered against a target in depth requiring changes in elevation. The beaten zones of each successive burst should be adjacent to each other if not overlapping (may be produced from either a tripod or bipod).


Traversing and Searching is

fire delivered against an oblique target requiring changes in both elevation and direction. The beaten zones of each successive burst should be adjacent to each other if not overlapping (may be produced from either a tripod or bipod).


Swinging Traverse is

Fire delivered against targets which require major changes in direction with little or no change in elevation. Fired at the cyclic rate of fire using the tripod. (The beaten zones of each successive burst need not be adjacent to each other.)


Free Gun is

Fire delivered against moving targets that require major changes in both direction and elevation. The beaten zones of each successive burst need not be adjacent to each other (can only be produced from a tripod or vehicle mount). The T&E is not used as the manipulation is done by the Gunner.


Eight Principles of Machine Gun Employment are

Interlocking Fires
Coordination of Fires
Mutual Support


Pairs is

We attempt to employ machine guns in pairs at all times. Guns employed in pairs should not be separated by intervening terrain. 35 meters is the optimal separation between the two weapons systems, terrain dictating. This allows us to duplicate fires to ensure continuous fire support even if one gun goes down. This also gives us “talking guns”, giving us constant fires on the target and uninterrupted fires during immediate action drills or if a gun goes down. A SAW can be integrated to the pairs if needed.


Interlocking Fires is

Reinforce and double the firepower employed across the units frontage. This also ensures no area goes uncovered, especially when grazing fires intersect


Coordination of Fires is

Dictates use of appropriate weapons to fire on appropriate targets. This allows maximum effectiveness of all weapons systems employed, to conserve ammunition, and ensure all machine gun fires are delivered at the appropriate time and place. Coordination should be made with other direct fire weapons, indirect fire assets, obstacle plan, etc.


Mutual Support is

The weapons systems need to be able to support each other. If one weapon is overrun or fails, the other weapon needs to be able to fire the mission.


Defilade is

Defilade allows us to fire the gun behind the mask of terrain outside the effects and observation of the enemy. This allows us to increase survivability of the position, the gun and the crew.


Enfilade is

Whenever we utilize machine guns, we attempt to achieve enfilading fires upon our enemy. By enfilade fires we mean that the long axis of the beaten zone coincides with the long axis of the target.


Economy is

By economy, we mean economy of our fires. We utilize the appropriate weapons systems in accordance with the threat. We will not open up with the M240 if we get attacked by a single enemy soldier. We establish engagement criteria for our crew served weapons to conserve ammunition, make sure the weapon system is appropriate to the threat and to ensure weapon system and crew survivability.


Protection is

Obvious considerations need to be taken in the construction of machine gun positions in order to ensure maximum survivability of the crew. Once the guns are ordered to engage, they will obviously become a focal point of the enemy. Cover and concealment are critical. The construction must be robust as well as moved frequently in order to ensure the continued support of their fires.


Machine Gun Fighting Positions are

Primary Position
Alternate Position
Supplemental Position
L-Shape Fighting Position
T-Shaped Fighting Position
Horse-Shoe Fighting Position
Two Hole Fighting Position


Primary Position is

The position from which the gun will fire it’s primary sector of fire


Alternate Position is

A secondary position from which the gun will fire it’s primary sector of fire


Supplemental Position is

Another separate prepared position from which the gun fires a secondary or alternate sector of fire.


L-Shape Fighting Position is

When only one sector of fire is assigned, only one half of the position is dug (L-shape) (see diagram below).
The PDF or FPL (the machine gun’s mission) must parallel either arm of the “L.” The L-shaped position should always be improved upon to make a “T” or horseshoe-shaped position.


T-Shaped Fighting Position is

The most preferred position to employ. This position will provide both primary and secondary sectors of fire. When employing the M240B, the tripod is used on the side covering the primary sector of fire. The bipod legs are used when covering the secondary mission. When switching from primary mission to secondary mission, the tripod stays in place and the weapon itself is moved to engage the targets.


When digging a T-Shaped Position, the hole is

dug armpit deep. When cover to the front is high enough, spoil is used to build up the flanks and the rear. Grenade sumps should be located at the end of each leg of the position.


Horse-Shoe Fighting Position is

The open end of the horseshoe is toward the enemy (see diagram below). This allows for easy 180-degree traverse across the frontage, but provides less frontal cover than the T-shaped position. Protection from indirect fire greater than the "T"-shaped position. The firing platform is located within the horseshoe. Spoilage is used to provide cover all around the position


Two Hole Fighting Position is

Uses two one-man fighting holes at 90-degree angles (see diagram below). Provides excellent protection for the gunner and assistant gunner but allows only limited traverse of the gun. Each hole is dug as a standard one-man fighting hole. When switching from the primary to the alternate sectors of fire, the gunner and the assistant gunner switch roles.


3 Support Relationships are

General Support
Direct Support


General Support is

A unit commander may task a subordinate unit to a general support mission. This is defined as “that support which is given to the supported force as a whole and not to any particular subdivision thereof” according to MCRP 5-2A. If a unit is designated to be in General Support, of another unit, it will provide fires to assist the supported units’ scheme of maneuver.


Direct Support is

A unit in direct support of another unit is assigned the mission of providing the support requested directly to the supported unit. The unit being supported directly (a rifle platoon, for example) is assigned fires directly supporting the platoon (Main Effort). The supported unit commander assigns the guns a mission and targets; however, tactical control still remains with the Machine Gun Section Leader.


Attachment is

Attachment is the placement of a unit in an organization where such placement is relatively temporary. The organization to which a unit is attached assumes complete tactical and administrative control over the unit, subject to any limitations (usually time) stipulated in the attachment order.


Classification of Offensive Fires are

Close Supporting Fire
Long Range Fires
Flank Protection Fires
Fires in Support of Consolidation


Close Supporting Fire is

Fires delivered against enemy objectives directly opposing the advance of the attacking rifle units.
Some considerations to take into account when employing these types of fires include
 Rates of fire
 Location of lead trace of maneuver element
 Signal plan for commencing, shifting, and ceasing fires


Long Range Fires

Fires that are delivered against targets to the rear of enemy forward position that may directly influence the main effort attack on the primary objective. Terrain and weapon permitting, long range fires are often assigned to machineguns when they can no longer provide close supporting fires to the attack.


Flank Protection Fires is

When the advance or location of a unit exposes their flank, the machine guns may be tasked with protecting it.


Fires in Support of Consolidation is

Enemy counterattack should be expected following seizure of an objective. Machine guns are used to protect the unit's consolidation and reorganization. Employment of the guns on the objective should be planned and rapidly executed.
Many of the machine guns will have to be displaced from SBF positions.


Displacement Considerations are

MORT, (Method, Objective, Route and Time).


Method (concerning Displacement Considerations) is

Echelon: By echelon, we essentially mean “leap frogging” those elements to the new position.

By Unit: In an instance where security en-route to the objective is not as much of a factor, the machine gun element may be ordered to displace directly to the parent units position in order to provide the immediate additional firepower of the machine guns in support of consolidation.


Objective (concerning Displacement Considerations) is

The unit will be forced or directed to move to one of two types of locations. Once the maneuver element has completed the assault upon the tactical objective, the unit leader may task the machine gun element to move to their location in order to provide addition fires in support of consolidation. An additional consideration may be a secondary support by fire position in order to continue support of an attack after the initial position has become untenable.


Route (concerning Displacement Considerations) is

A route is a crucial consideration for the unit leader when planning the displacement of the machine gun element. Higher can assign these routes based on operational knowledge of the area, or it can be left to the discretion of the subordinate unit leader in charge of those Marines who may have better situation awareness of the battlefield as it now stands.


Time (concerning Displacement Considerations) is

Careful consideration must be given to when that unit will displace. We must plan for when we will need their fires again if displacing to a secondary SBF, or how long we will be able to support consolidation while the machine gun assets displace to the rest of the unit. Another important aspect is the signal plan surrounding that displacement. We must make sure that the signal is clearly communicated in the order and is able to be executed on the battlefield. If a unit fails to receive proper communication we may not have fires when we need them or expose those Marines to unnecessary risks by unmasking and moving too early.


Principal Direction of Fire is

PDF, or a principle direction of fire. The weapons primary focus is covering a likely avenue of approach, key piece of terrain, or whatever object of interest that unit leader assigns it. Now, the weapon will also have a left and right lateral limit that will allow the gunner to engage targets of opportunity within that sector of fire, but unless that situation arises, that weapon is laid on that PDF, ready to engage on at that point. Generally speaking a PDF attempts to achieve frontal enfilading fire.


Final Protective Line is

The FPL is only fired in accordance with the unit commander giving the order to fire his Final Protective Fires. Again, a sector of fire is given, with the instruction that in accordance with engagement criteria that gun can engage a target of opportunity. But again, the primary mission of that gun is to be laid on that designated FPL. The FPL should achieve flanking enfilade fire.


Individual Weapon Considerations is

M240B: Terrain is one of the biggest factors when deciding the role these weapons will play. If terrain greatly constitutes grazing fire, push the weapons out to the flank where the greatest amount of grazing fire can be achieved while interlocking the fires with adjacent guns and assign the mission of a FPL. If terrain is canalizing, allowing limited access to your position, consider assigning the guns a PDF, greatly improving the coverage on those areas most likely to be advanced upon.
M2 .50 Caliber HMG: Its direct fire characteristics dictate employment very similar to considerations used with the M240B, with the greatest considerations being its anti-armor capabilities and penetration
MK19 MOD 3: The MK19 differs most greatly in the fact that we cannot achieve grazing fires based on the nature of the ammunition. That being said, the weapon is an excellent choice to assign a PDF, such as choke points, obstacles and avenues of approach, as well as dead space.


Offensive Considerations for Machineguns is

M240B: Best and most often used in a support by fire position to provide a heavy volume of accurate suppressive fire. If terrain is viable, consider the use of an observer in order to allow the guns to be employed from defilade. The weapon can also be taken into the assault, utilizing either the bipod or the tripod.
M2 .50 Caliber Heavy MG: This weapon can also be employed as a support by fire asset, especially when the enemy is utilizing fortified positions. Also used against mechanized or lightly armored assets, taking account the increased penetration of the rounds available.
MK 19 MOD 3 40mm Automatic Grenade Launcher: Extremely effective against personnel due to its 15m ECR from the 40mm round. Very effective combined with an observer to deliver indirect fires. Anti-armor capability of 2 inches of homogenous steel out to 2200 m. Like the other two weapon systems, also able to be utilized in SBF position.


Fire Commands are









Alert (concerning fire commands) is

Mandatory part of the order.

-Fire Mission = Both guns fire

-Number One, Fire Mission- Only one gun fires

-Fire Mission, Number Two- Gun number two fires the mission, but gun number one tracks it and is prepared to fire on command.


Direction (concerning fire commands) is

Only when not obvious or in an instance when firing from defilade under the direction of an observer.


Description (concerning fire commands) is

Given to allow the gunner and A-gunner to more accurately orient on the target.


Range (concerning fire commands) is

Cannot be over emphasized. Several field expedient methods that have already been discussed elsewhere in your instruction. Sooner correct range is acquired, the quicker the effects of those rounds are felt by the enemy.


Assignment (concerning fire commands) is

Assignment is only used if specific requirements are needed to divide the target, assign a class of fire, or designate a rate of fire


Control (concerning fire commands) is

Mandatory in order to coordinate proper initiation and control of fires. Subsequent commands will be made by the unit leader in order make corrections on the impacts of the rounds, rates of fire, or even to shift or cease fires


Range Cards is

a diagram drawn to record the firing data and mission of that machine gun position and also serves as a document to assist in defensive fire planning. A range card is constructed of a sketch of the position and also of the terrain that lies to the front of the weapon system.


One key element of creating a range card is

walking the terrain we are about to document. This allows to properly annotate our dead space. This is especially important when recording our FPL.


The range is recorded to

the near and far ends of the dead space and to the maximum extent of graze along the FPL. The firing data needed to fire this target as well as the magnetic azimuth is recorded on the range card.