Appendix C - Machine Gun Employment and Theory

Whether organic to the unit or attached, machine guns provide the heavy volume of close and continuous fire needed to achieve fire superiority. They are the Infantry platoon’s most effective weapons against a dismounted enemy force. These formidable weapons can engage enemy targets beyond the capability of individual weapons with controlled and accurate fire. This appendix addresses the M249 light machine gun and M240 medium machine gun organic to the Infantry rifle platoon.

Technical Data

C-1. Leaders must know the technical data of their assigned weapon systems and associated ammunition to maximize their killing and suppressive fires while minimizing the risk to friendly forces. This section discusses machine gun technical data of the Infantry platoon and squad.

C-2. Machine gun fire has different effects on enemy targets depending on the type of system, ammunition used, range to target, and nature of the target. It is important gunners and leaders understand technical aspects of each system and different ammunition available to ensure the machine guns are employed in accordance with their capabilities. Machine guns use several different types of standard military ammunition. Soldiers should use only authorized ammunition manufactured to U.S. and North Atlantic Treaty Organization specifications.

C-3. The following paragraphs discuss the technical data for the tactical employment of M249 and M240-series machine guns. See the specific publication of the machine guns listed in table C-1 on page C-2 for complete information regarding their technical data.

Table C-1. Machine gun technical data

M249 Light Machine Gun

C-4. The M249 light machine gun is organic to the Infantry rifle squad. It provides squads with a light automatic weapon for employment during assault. (See figure C-1.) The M249 also can be used in the medium machine gun role in defensive missions or support by fire position. The M249 fires from the bipod, the shoulder, the hip, or from the underarm position. The hip and underarm positions normally are used for close in fire during an assault when the M249 gunner is on the move and does not have time to set the gun in the bipod position. It is best used when a high rate of fire is needed immediately. Accuracy of fire is decreased when firing from either the hip or shoulder.

Figure C-1. M249 light machine gun, bipod mode

C-5. Available M249 ammunition is classified as follows (see table C-2):

M855 5.56-mm ball. For use against light materiel, utility/unarmored vehicles, and personnel, but not armored vehicles.
M856 5.56-mm tracer. Generally used for adjustments after observation, incendiary effects, and signaling. When tracer rounds are fired, they normally are mixed with ball ammunition in a ratio of four ball rounds to one tracer round.

Table C-2. M249 light machine gun ballistic data

M240B Medium Machine Gun

C-6. Two medium machine guns and crews are found in the weapons squad. (See figure C-2 on page C-4.) The M240B can be fired in the assault mode in emergencies, but normally is fired from the bipod or tripod platform. It also can be vehicle mounted. Platoon leaders (through their weapons squad leader) employ the M240B medium machine guns with a rifle squad to provide long range, accurate, sustained fires against dismounted Infantry, apertures in fortifications, buildings, and lightly armored vehicles. The M240B also provides a high volume of short-range fire in self-defense against aircraft. Machine gunners use point, traversing, searching, or searching and traversing fire to kill or suppress targets.

Figure C-2. M240B medium machine gun, bipod- and tripod-mounted

C-7. Available M240 medium machine gun ammunition is classified as follows (see table C-3):

M80 7.62-mm ball. For use against light materiel and personnel.
M61 7.62-mm armor piercing. For use against lightly armored targets.
M62 7.62-mm tracer. For observation of fire, incendiary effects, signaling, and for training. When tracer rounds are fired, they normally are mixed with ball ammunition in a ratio of four ball rounds to one tracer round.

Table C-3. M240 medium machine gun ammunition

M240L Medium Machine Gun

C-8. The M240L short barrel reduces the length of the standard barrel by 4 inches and the weight by .5 pounds, while maintaining accurate fire at extended ranges. The shorter barrel improves mobility in military operations in urban terrain environments. The M240L is 5.1 pounds lighter than the M240B and is 5.6 pounds lighter with the short barrel installed. (See figure C-3.)

Note. The M240L incorporates titanium construction and alternative manufacturing methods for fabricating major M240B components to achieve significant weight savings. These improvements reduce the Soldier’s combat load while allowing easier handling and movement of the weapon.

Figure C-3. M240L Medium machine gun, bipod mode

Combat Techniques Of Fire

C-9. Combat techniques of fire illustrates the characteristics of machine gun fire, the types of enemy targets engaged, and how to apply machine gun fire on those enemy targets. Read the appropriate publications as shown in table C-1 on page C-2 for more weapon-specific information on engaging enemy targets with a particular machine gun.

Characteristics Of Fire

C-10. The gunner’s or leader’s knowledge of the machine gun is not complete until the gunner or leader learns about the action and effect of the projectiles when fired. The following definitions will help the leader, gunner, and assistant gunner understand the characteristics of fire of the weapons squad’s machine guns.

Line of Sight

C-11. Line of sight is an imaginary line drawn from the firer’s eye through the sights to the point of aim. Example line of sight restrictions can be obstacles, terrain, and vegetation driven.

Burst of Fire

C-12. A burst of fire is a number of successive rounds fired with the same elevation and point of aim when the trigger is held to the rear. The number of rounds in a burst can vary depending on the type of fire employed.

Trajectory

C-13. Trajectory is the curved path of the projectile in its flight from the muzzle of the weapon to its impact. The major factors influencing trajectory are the velocity of the round, gravity, rotation of the round, and air resistance. As the range to the target increases, so does the curve of trajectory. (See figure C-4 on page C-6.)

Figure C-4. Trajectory and maximum ordinate

Cone of Fire

C-14. The cone of fire is the pattern formed by the different trajectories in each burst as they travel downrange. Vibration of the weapon and variations in ammunition and atmospheric conditions all contribute to the trajectories making up the cone of fire. (See figure C-5.)

Figure C-5. Cone of fire and beaten zone

Beaten Zone

C-15. The beaten zone is the elliptical pattern formed when the rounds within the cone of fire strike the ground or target. (See figure C-5.) The size and shape of the beaten zone change as a function of the range to and slope of the target but is normally oval or cigar shaped, and density of rounds decreases toward the edges. Gunners and automatic riflemen should engage targets to take maximum effect of the beaten zone. The simplest way to do this is to aim at the center base of the target. Most rounds will not fall over (beyond) the target and falling short creates ricochets into the target.

C-16. Effective beaten zone. Leaders and gunners strive to position their gun teams to achieve an effective beaten zone. Because of dispersion, only part of the beaten zone in which 85 percent of the rounds fall is considered the effective beaten zone.

C-17. Effect of range on the beaten zone. As the range to the target increases, the beaten zone becomes shorter and wider. Conversely, as the range to the target decreases, the beaten zone becomes longer and narrower. (See table C-4.)

C-18. Effect of slope on the beaten zone. The length of the beaten zone for given ranges varies according to the slope of the ground. On rising ground, the beaten zone becomes shorter but remains the same width. On ground sloping away from the gun, the beaten zone becomes longer but remains the same width.

Table C-4. Beaten zones of the M240

Danger Space

C-19. This is the space between the muzzle of the weapon and target where trajectory does not rise above 1.8 meters (the average height of a standing Soldier) including the beaten zone. When firing over level or uniformly sloping terrain danger space would include the M240 and M249 attaining grazing fires (see paragraph C-23) to a maximum of 600 meters. Gunners should consider the danger space of weapons when planning overhead fires. Plunging fire (see paragraph C-24) occurs when there is little or no danger space from the muzzle of the weapon to the beaten zone.

Surface Danger Zone

C-20. Surface danger zones were developed for each weapon and are defined as the area in front, back, or side of the muzzle of the weapon providing a danger to friendly forces when the weapon is fired. The surface danger zone is not just the area comprising the cone of fire as it moves downrange. It also involves the possible impact area on both sides of the gun target line and possible dispersion of materiel caused by the strike of the rounds, the possible ricochet area, and areas to the rear adversely affected by the effects of firing the weapon. (See figure C-6 on page C-8.)

C-21. Surface danger zones were developed primarily for ranges and must be complied with when training, but they also should be complied with in combat, when possible, to minimize risk to friendly forces. (See DA Pam 385-63 for additional information.)

Figure C-6. Surface danger zones for machine guns

Classifications Of Automatic Weapons Fire

C-22. The U.S. Army classifies automatic weapons fires with respect to the ground, target, and weapon. Fires with respect to the ground include grazing and plunging fire.

Classification of Fires with Respect to the Ground

C-23. Grazing fires. Automatic weapons achieve grazing fire when the center of the cone of fire does not rise more than 1 meter above the ground. Grazing fire is employed in the final protective line (FPL) in the defense and is only possible when the terrain is level or sloping uniformly. When firing over level or uniformly sloping terrain, the machine gun M240-series and M249 can attain a maximum of 600 meters of grazing fire. Typically, an FPL is planned where the gunner can achieve grazing fire. The unit plans indirect fires, including M320s, to cover dead space along the FPL.

C-24. Plunging fires. Plunging fire occurs when there is little or no danger space from the muzzle of the weapon to the beaten zone. It occurs when weapons fire at long range, when firing from high ground to low ground, when firing into abruptly rising ground, or when firing across uneven terrain, resulting in a loss of grazing fire at points along the trajectory. (See figure C-7.)

Note. Folds or depressions in the ground preventing a target from being engaged from a fixed position are termed dead space. Paragraph C-72 discusses methods of determining dead space.

Figure C-7. Classes of fires with respect to the ground

Classification of Fires with Respect to the Target

C-25. Fires with respect to the target include enfilade, frontal, flanking, and oblique fire. (See figure C-8 on page C-10, figures C-9 and C-10 on page C-11.) These targets normally are presented to gun teams by the enemy and must be engaged as they are presented. For example, if the enemy presents its flank to the gun crew as it moves past their position from the left or right, the gun crew will have no choice but to employ flanking fire on the enemy.

C-26. Leaders and gunners strive to position their gun teams where they can best take advantage of the machine gun’s beaten zone with respect to an enemy target. Channeling the enemy by use of terrain or obstacles so they approach a friendly machine gun position from the front in a column formation is one example. In this situation, the machine gun would employ enfilade fire on the enemy column, and effects of the machine gun’s beaten zone would be much greater than if it engaged enemy column from the flank.

C-27. Enfilade fire. Fires that occur when the long axis of the beaten zone coincides or nearly coincides with the long axis of the target. It can be frontal fire on an enemy column formation or flanking fire on an enemy line formation. This is the most desirable class of fire with respect to the target because it makes maximum use of the beaten zone. Leaders and gunners always should strive to position the guns to the extent possible engaging enemy targets with enfilade fire.

C-28. Frontal fire. Fires that occur when the long axis of the beaten zone is at a right angle to the front of the target. This type of fire is highly desirable when engaging a column formation. It then becomes enfilade fire as the beaten zone coincides with the long axis of the target. Frontal fire is not as desirable when engaging a line formation because most of the beaten zone normally falls below or after the enemy target.

C-29. Flanking fire. Fires that are delivered directly against the flank of the target. Flanking fire is highly desirable when engaging an enemy line formation. It then becomes enfilade fire as the beaten zone will coincide with the long axis of the target. Flanking fire against an enemy column formation is least desirable because most of the beaten zone normally falls before or after the enemy target.

C-30. Oblique fire. Gunners and automatic riflemen achieve oblique fire when the long axis of the beaten zone is at an angle other than a right angle to the front of the target. Oblique fire is less desirable than enfilade fire with respect to the target because it does not maximize the use of the beaten zone.

Figure C-8. Classes of fire with respect to the target

Figure C-9. Frontal fire and flanking fire

Figure C-10. Oblique fire and enfilade fire

Classification of Fires with Respect to the Machine Gun

C-31. Fires with respect to the weapon include fixed, traversing, searching, traversing and searching, swinging traverse, and free gun fires. (See figure C-11 on page C-13.)

C-32. Fixed fire. Fire is delivered against a stationary point target when the depth and width of the beaten zone covers the target with little or no manipulation needed. After the initial burst, the gunners follow changes or movement of the target without command.

C-33. Traversing fire. Traversing disperses fires in width by successive changes in direction, but not elevation. It is delivered against a wide target with minimal depth. When engaging a wide target requiring traversing fire, the gunner selects successive aiming points throughout the target area. These aiming points should be close enough together to ensure adequate target coverage. However, they do not need to be so close as to waste ammunition by concentrating a heavy volume of fire into a small area.

C-34. Searching fire. Searching distributes fires in-depth by successive changes in elevation. It is employed against a deep target or a target having depth and minimal width, requiring changes in only the elevation of the gun. The amount of elevation change depends upon the range and slope of the ground.

C-35. Traversing and searching fire. This class of fire is a combination in which successive changes in direction and elevation result in the distribution of fires both in width and depth. It is employed against a target whose long axis is oblique to the direction of fire.

C-36. Swinging traverse. Swinging traverse fire is employed against targets requiring major changes in direction but little or no change in elevation. Targets may be dense, wide, in close formations moving slowly toward or away from the gun, or vehicles or mounted troops moving across the front. If tripod mounted, the traversing slide lock lever is loosened enough to permit the gunner to swing the gun laterally. When firing swinging traverse, the weapon normally is fired at the cyclic rate of fire. Swinging traverse consumes a lot of ammunition and the weapon does not have a beaten zone because the rapid traverse distributes the impact of the rounds laterally across a wide area.

C-37. Free gun. Fire delivered against moving targets rapidly engaging with fast changes in both direction and elevation. Examples are aerial targets, vehicles, mounted troops, or Infantry in relatively close formations moving rapidly toward or away from the gun position. When firing free gun, the weapon normally is fired at the cyclic rate of fire. Free gunfire consumes a lot of ammunition and does not have a beaten zone because each round seeks its own area of impact.

Figure C-11. Classes of fire with respect to the gun

Application Of Fire

C-38. Application of fire consists of the methods the gunner uses to cover an enemy target area. Training these methods of applying fire can be accomplished only after the weapons squad leader and gunners have learned how to recognize the different types of targets they may find in combat. They also must know how to distribute and concentrate their fire, and how to maintain the proper rate of fire. Normally, the gunner is exposed to two types of targets in the squad or platoon area of operations (AO): enemy soldiers and supporting automatic weapons. Leaders must ensure targets have priority and are engaged immediately.

C-39. Machine gun fire must be distributed over the entire target area. Improper distribution of fire results in gaps allowing the enemy to escape or use its weapons against friendly positions without opposition.

C-40. The method of applying fire to a target is generally the same for either a single gun or a pair of guns. Direct lay is pointing the gun for direction and elevation, so the sights are aligned directly on the target. Fire is delivered in width, depth, or in a combination of the two. To distribute fire properly, gunners must know where to aim, how to adjust their fire, and direction to manipulate the gun. The gunner must aim, fire, and adjust on a certain point of the target. Binoculars may be used by the leader to facilitate fire adjustment.

Sight Picture

C-41. A correct sight picture has the target, front sight post, and rear sight aligned. The sight picture has sight alignment and placement of the aiming point on the target. The gunner aligns the front sight post in the center of the rear sight and aligns the sights with the target. The top of the front sight post is aligned on the center base of the target.

Beaten Zone

C-42. The gunner ensures throughout firing the center of the beaten zone is maintained at the center base of the target for maximum effect from each burst of fire. When this is done, projectiles in the upper half of the cone of fire will pass through the target if it has height, and projectiles in the lower half of the beaten zone may ricochet into the target. (See figure C-12.)

Figure C-12. Line of aim and placement of center of beaten zone on target

C-43. The gunner must move the beaten zone in a certain direction over the target. The direction depends on the type of target and whether the target is engaged with a pair of guns or a single gun. When engaging targets other than point targets with a pair of guns, the targets are divided so fire is distributed evenly throughout the target area. Fire delivered on point target, or a specific area of other target configurations is called concentrated fire.

Target Engagements

C-44. Gunners engage targets throughout their respective sectors. They must know how to engage all types of targets, either individually or with other gunners. When a single gunner is assigned targets, the gunner is responsible for covering the entire target. When a pair of gunners engage an enemy target, each gunner normally is responsible for covering one half of the target. The gunners must be prepared to engage the entire target should the other gun go down.

Enemy Troops and Light Vehicles

C-45. Gunners’ targets in combat are normally enemy troops and light vehicles in various formations or displacements, which require distribution and concentration of fire. These targets often have both width, depth, and application of machine gun fire is designed to cover the area in which the enemy is known or suspected to be completely. These targets may be easy to see or may be indistinct and difficult to locate. The size of the target, stated in terms of the number of aiming points required to engage it completely, determines its type.

Self-Defense Against Hostile Low-Flying, Low-Performance Aircrafts

C-46. The machine gun can provide units with a self-defense capability against hostile low-flying, low-performance aircraft. These guns are employed in the air defense role as part of the unit’s local defense. The machine guns are not components of an integrated and coordinated air defense system. Unless otherwise directed, hostile aircraft within range of the gun (about 800 meters maximum effective range) should be engaged. The decision will be made by the commander or leader. Typical targets are surveillance, reconnaissance, and liaison aircraft; troop carriers; helicopters; and drones.

C-47. Employment of machine guns used for air defense is guided by the following defensive design factors:

Defensive design should produce an equally balanced defense in all directions unless a forced route of ingress/egress exists.
Machine guns should be positioned so the maximum number of targets can be engaged, continuous fire can be delivered, and likely routes of approach are covered.
Machine guns used to defend march columns should be interspersed in the convoy, with emphasis on the lead and rear elements.

Selection and Engagement Control

C-48. These actions depend upon visual means. The sites selected for guns must provide maximum observation and unobstructed sectors of fire. Units furnished machine guns in sufficient numbers should position them within mutually supportive distances of 90 to 360 meters. Each gun is assigned a primary and secondary sector of fire. Weapon crews maintain constant vigilance in their primary sectors of fire, regardless of the sector in which the guns are engaged.

Distributed and Concentrated Fire

C-49. Distributed fire is delivered in width and depth such as at an enemy formation. Concentrated fire is delivered at a point target such as an automatic weapon or an enemy fighting position.

Rate of Fire

C-50. The size and nature of the enemy target determines how machine gun fire is applied. Automatic weapons fire in one of three rates: rapid, sustained, or cyclic. The rates of fire for each machine gun are shown in table C-1 on page C-2. The situation normally dictates the rate used, but the availability of ammunition and need for barrel changes play important roles as well. The rate of fire must be controlled to cover the target adequately, but not waste ammunition or destroy the barrel.

Rapid Fire

C-51. Rapid rate of fire places an exceptionally high volume of fire on an enemy position. Machine gunners normally engage targets at the rapid rate to suppress the enemy quickly. Rapid fire requires more ammunition than sustained fire and requires frequent barrel changes.

Sustained Fire

C-52. Once the enemy has been suppressed, machine gunners fire at the sustained rate. Sustained fire conserves ammunition and requires only infrequent barrel changes, but it might not be enough volume of fire to suppress or destroy.

Cyclic Rate of Fire

C-53. To fire the cyclic rate, the gunner holds the trigger to the rear while the assistant gunner feeds ammunition into the weapon. This normally is used only to engage aerial targets in self-defense or to fire the FPLs in the defense to protect the perimeter. This produces the highest volume of fire the machine gun can fire but can permanently damage the machine gun and barrel and should be used only in case of emergency.

Limited Visibility

C-54. Gunners have difficulty detecting and identifying targets during limited visibility. The leader’s ability to control the fires of the gunners’ weapons also is reduced; therefore, the leader may instruct the gunners to fire without command when targets present themselves.

C-55. Gunners should engage targets only when they can identify the targets, unless ordered to do otherwise. For example, if one gunner detects a target and engages it, the other gunner observes the area fired upon and adds fire only if the gunner can identify the target or if ordered to fire.

C-56. Often referred to as engagement criteria, a trigger specifies the circumstances in which subordinate elements should engage. The circumstances can be based on a friendly or enemy event. For example, the trigger for a friendly platoon to initiate engagement could be three or more enemy combat vehicles passing or crossing a given point or line. This line can be any natural or man-made linear feature, such as a road, ridgeline, or stream. It may also be a line perpendicular to the unit’s orientation, delineated by one or more reference points.

C-57. Tracer ammunition helps a gunner engage targets during limited visibility and should be used if possible. It is important to note in certain circumstances the enemy will have an easy time identifying the machine gun’s position if the gunner uses tracer ammunition. The need to engage targets must be balanced with the need to keep the guns safe before deciding to employ tracers. If firing unaided or during limited visibility, gunners must be trained to fire low at first and adjust upward. This overcomes the tendency to fire high.

C-58. When two or more gunners are engaging linear targets, linear targets with depth, or deep targets, they do not engage these targets as they would when visibility is good. With limited visibility, the center and flanks of these targets may not be defined clearly. Therefore, each gunner observes the tracers and covers what each gunner believes to be the entire target.

Techniques

C-59. Techniques of fire include assault fire, overhead fire, and fire from a defilade position. Generally, only automatic rifles use assault fire (see paragraphs C-126 to C-128 when the medium machine gun is used in the assault element).

Assault Fire

C-60. Automatic riflemen use assault fire when in close combat. Assault fire involves firing without the aid of sights using the hip, shoulder, and underarm positions. The underarm position is best when rapid movement is required. In all three positions, automatic riflemen adjust their fire by observing the tracer and impact of the bullets on the target area. Additional considerations for automatic riflemen using assault fire include:

Maintaining alignment with the rest of the assault element.
Reloading rapidly.
Aiming low and adjusting the aim upward toward the target.
Distributing fires across the objective when not engaging enemy automatic weapons.
Automatic riflemen can control rates of fire by firing short bursts as they advance, for instance firing every other left step, every left step, or every step.

Overhead Fire

C-61. Gunners can use overhead fire when there is sufficient low ground between the machine gun and target area of the maneuver friendly forces. A machine gun on a tripod is capable of delivering this type of fire because of the small and uniform dispersion of the cone of fire. Gunners must accurately estimate range to the target and establish a safety limit imaginary line parallel to the target where fire would cause casualties to friendly Soldiers. Gun crews and leaders must be aware of this safety limit. Leaders must designate signals for lifting or shifting fires. Gunners should not attempt overhead fires if the terrain is level or slopes uniformly, if the barrel is badly worn, or if visibility is poor.

C-62. Gunner’s rule. The gunner’s rule can be applied when the friendly troops are at least 350 meters in front of the gun position and range to the target is 850 meters or less. (See figure C-13.) The tripod mounted machine gun rule follows:

Lay the gun on the target with the correct sight setting to hit the target.
Without disturbing the lay of the gun, set the rear sight at a range of 1,600 meters.
Look through the sights and notice where the new line of aim strikes the ground. This is the limit of troop safety. When the feet of the friendly troops reach this point, fire must be lifted or shifted.

Figure C-13. Application of gunner’s rule

C-63. Leader’s rule. When the range to the target is greater than 850 meters, overhead fire should be delivered only in an emergency. Even then, fire should extend only to a range at which the tracers or strike of the bullets can be seen by the gunner. In this situation, the leader’s rule applies. (See figure C-14.) The platoon or section leader uses the leader’s rule only when the target is greater than 850 meters. The rule follows:

Select a point on the ground where it is believed friendly troops can advance with safety.
Determine the range to this point by the most accurate means available.
Lay the gun on the target with the correct sight setting to hit the target.
Without disturbing the lay of the gun, set the rear sight to 1,600 meters or the range to the target plus 500 meters, whichever is the greater of the two ranges. Under no conditions should the sight setting be less than 1,500 meters.
Note the point where the new line of aim strikes the ground:
- If it strikes at the selected point, that point marks the limit of safety.
- If it strikes short of the selected point, it is safe for troops to advance to the point where the line of aim strikes the ground and to an unknown point beyond. If fire is called for after friendly troops advance farther than the point where the line of aim strikes the ground, this farther point is determined by testing new selected points until the line of aim and selected point coincide.
- If it clears the selected point, it is safe for troops to advance to the selected point and to an unknown point beyond. If it is advantageous to have troops advance beyond the selected point, this farther point must be determined by testing new selected points until the line of aim and selected point coincide. This point marks the line of safety.

Figure C-14. Application of leader’s rule

Fire from a Defilade Position

C-64. Defilade positions protect gunners from frontal or enfilading fires. (See figure C-15 on page C-20.) Cover and concealment may not provide the gunner a view of some or all of the target area. In this instance, some other member of the platoon or squad must observe the impact of the rounds and communicate adjustments to the gunner. (See figure C-16 on page C-20.) Gunners and leaders must consider the complexity of laying on the target. They also must consider the gunner’s inability tom ake rapid adjustments to engage moving targets, which includes the ease with which targets are masked and the difficulty in achieving grazing fires for an FPL.

Figure C-15. Defilade positions

Figure C-16. Observer adjusting fire

Predetermined Fires

C-65. Predetermined fires organize the battlefield for gunners. They allow the leader and gunner to select potential targets or target areas most likely to be engaged or have tactical significance. This includes dismounted enemy avenues of approach, likely positions for automatic weapons, and probable enemy assault positions.

Terminology

C-66. The terminology used by gunners for predetermined fires maximizes the effectiveness of the machine gun during good as well as limited visibility. It enhances fire control by reducing the time required to identify targets, determine range, and manipulate the weapon onto the target. Abbreviated fire commands and previously recorded data enable the gunner to aim or adjust fire on the target quickly and accurately. Selected targets should be fired on in daylight whenever practical to confirm data. The standard range card (GTA 07-10-001 [Machine Gunner’s Card] outlines the process in preparing a machine gun range card for the weapon’s primary position) identifies the targets and provides a record of firing data. DA Form 5517 provides a record of firing data and aids defensive fire planning. If time permits, the gunner also prepares standard range cards for the weapon’s alternate and supplementary positions. Gunners need to know several terms associated with predetermined fire.

Sector of Fire

C-67. A sector of fire is that area assigned to a unit or weapon system in which it will engage the enemy according to the established engagement priorities (FM 3-90). Individual Soldiers and gunners normally are assigned a primary and a secondary sector of fire.

Planned Targets

C-68. The platoon leader or weapons squad leader will designate planned targets within the primary and secondary sectors of fire. The gunner will number them, determine firing data, and can then fire them as directed whether visible, on command, or in periods of limited visibility.

Final Protective Line

C-69. An FPL is a predetermined line along which grazing fire is placed to stop an enemy assault. If an FPL is assigned, (see figure C-17) the machine gun is sighted along it except when other targets are being engaged. An FPL becomes the machine gun’s part of the unit’s FPFs. An FPL is fixed in direction and elevation. However, a small shift for search must be employed to prevent the enemy from crawling under the FPL and to compensate for irregularities in the terrain or the sinking of the tripod legs into soft soil during firing. Fire must be delivered during all conditions of visibility. The FPL is always the left or right limit of an assigned primary sector of fire.

C-70. A good FPL covers the maximum area with grazing fire. Grazing fire can be obtained over various types of terrain out to a maximum of 600 meters. To obtain the maximum extent of grazing fire over level or uniformly sloping terrain, the gunner sets the rear sight at 600 meters. The gunner then selects a point on the ground the gunner estimates to be 600 meters from the machine gun, and the gunner aims, fires, and adjusts on that point. To prevent enemy soldiers from crawling under grazing fire, the gunner searches (downward) by lowering the muzzle of the weapon.

Figure C-17. Final protective line control measure symbol

Principal Direction of Fire

C-71. Principal direction of fire (known as PDF) is assigned to a gunner to cover an area having good fields of fire or has a likely dismounted avenue of approach. It also provides mutual support to an adjacent unit. Machine guns are sited using the PDF if an FPL has not been assigned. If a PDF is assigned and other targets are not being engaged, machine guns remain on the PDF. A PDF has the following characteristics:

It is used only if an FPL is not assigned; it then becomes the machine gun’s part of the unit’s FPFs.
When the target has width, direction is determined by aiming on one edge of the target area and noting the amount of traverse necessary to cover the entire target.
The gunner is responsible for the entire wedge-shaped area from the muzzle of the weapon to the target, but elevation may be fixed for a priority portion of the target.

Note. Figure C-18 shows the sector of fire of an automatic rifle or machine gun. In this example, the PDF is along the left side of the sector. The field A shows the equipment symbol for an automatic rifle or machine gun.

Figure C-18. Principal direction of fire control measure symbol

Dead Space and Grazing Fire

C-72. The extent of grazing fire and dead space may be determined in two ways. In the preferred method, the machine gun is adjusted for elevation and direction. A squad member then walks along the FPL while the gunner aims through the sights. In places where the Soldier’s waist (midsection) falls below the gunner’s point of aim, dead space exists. Hand and arm signals (see TC 3-21.60) must be used to control the Soldier who is walking and to obtain an accurate account of the dead space and its location. Another method is to observe the flight of tracer ammunition from a position behind and to the flank of the weapon.

Primary Sector of Fire

C-73. The primary sector of fire is assigned to the gun team to cover the most likely avenue of enemy approach from all types of defensive positions. Secondary sectors of fire, when there are no targets in the primary sector or when the leader needs to cover the movement of another friendly element, correspond to another element’s primary sector of fire to obtain mutual support. When used, the tripod will be set to fire into the primary sector of fire. If assigned, the FPL will generally be the left or right limit of the primary sector of fire.

Secondary Sector of Fire

C-74. The secondary sector of fire is assigned to the gun team to cover the second most likely avenue of enemy approach. It is fired from the same gun position as the primary sector of fire; however, the gun will probably have to be dismounted from the tripod to fire within the secondary sector of fire.

Field Expedient Techniques

C-75. When laying the machine gun for predetermined targets, the gunner can use field expedients as a means of engaging targets when other sources are not available. These can include following:

Base Stake Technique

C-76. A base stake is used to define sector limits and may provide the lay of the FPL or predetermined targets along a primary or secondary sector limit. This technique is effective in all visibility conditions. The gunner uses the following steps:

Defines the sector limits by laying the gun for direction along one sector limit and by emplacing a stake along the outer edge of the folded bipod legs. Rotates the legs slightly on the receiver, so the gunner takes up the “play.” Uses the same procedure for placing a stake along the opposite sector limit.
Lays the machine gun along the FPL by moving the muzzle of the machine gun to a sector limit. Adjusts for elevation by driving a stake into the ground so the top of the stake is under the gas cylinder extension. This allows a few mils of depression to cover irregularities in the terrain.
Lays the machine gun to engage other targets within a sector limit. Done in a primary sector by using the procedure described previously, except the gunner keeps the elevation fixed.

Notched-Stake or Tree-Crotch Technique

C-77. The gunner uses the notched-stake or tree-crotch technique with the bipod mount to engage predetermined targets within a sector or to define sector limits. This technique is effective during all conditions of visibility and requires little additional materiel. The gunner uses the following steps:

Drives either a notched stake or tree crotch into the ground where selected targets are anticipated. Places the stock of the machine gun in the nest of the stake or crotch and adjusts the weapon to hit the selected targets and to define the sector limits.
Digs shallow, curved trenches or grooves for the bipod feet. (These trenches allow for rotation of the bipod feet as the gunner moves the stock from one crotch or stake to another.)

Horizontal Log or Board Technique

C-78. This technique is used with the bipod or tripod mount to mark sector limits and engage wide targets. It is good for all visibility conditions and is best suited for flat, level terrain. The gunner uses the following steps:

Bipod-Mounted Machine Gun

C-79. Using a bipod-mounted machine gun, the gunner places a log or board beneath the stock of the weapon so the stock can slide across it freely. The gunner digs shallow, curved trenches or grooves for the bipod feet to allow rotation of the feet as the gunner moves the stock along the log or board. (The gunner may mark the sector limits by notching or placing stops on the log or board. The gunner uses the bipod firing position and grip.)

Tripod-Mounted Machine Gun

C-80. Using a tripod-mounted machine gun, the gunner places a log or boards beneath the barrel, positioning it so the barrel, when resting on the log or board, is at the proper elevation to obtain grazing fire. When appropriate, the gunner marks the sector limits as described of the bipod in the preceding paragraph. (This technique is used only if a traversing and elevating mechanism is not available.)

Fire Control

C-81. Fire control includes all actions of leaders and Soldiers in planning, preparing, and applying fire on a target. Leaders select and designate targets. They also designate the midpoint and flanks or ends of a target unless they are obvious to the gunner. Gunners fire at the instant desired. They then adjust fire, regulates the rate of fire, shift from one target to another, and cease fire. When firing, gunners should continue to fire until the target is neutralized or until signaled to do otherwise by their leader.

C-82. Predetermined targets, including the FPL or PDF, are engaged on order or by SOP. The signal for calling these fires normally is stated in the defensive order. Control these predetermined targets by using hand and arm signals, voice commands, or pyrotechnic devices. Gunners fire the FPL or PDF at the sustained rate of fire unless the situation calls for a higher rate. When engaging other predetermined targets, the sustained rate of fire also is used unless a different rate is ordered.

Methods Of Fire Control

C-83. The noise and confusion of battle may limit the use of some of the following fire control methods. Therefore, leaders must select a method or combination of methods to accomplish the mission.

Oral

C-84. The oral fire control method can be effective, but sometimes leaders may be too far away from the gunner, or the noise of the battle may make it impossible for them to hear. The primary means of the oral fire control method is the issuance of a fire command (see paragraph C-90).

Hand and Arm Signals

C-85. Hand and arm signals are an effective fire control method when the gunner can see the leader. All gunners must know the standard hand and arm signals. The leader gets the gunner’s attention and points to the target. When the gunner returns the READY signal, the leader commands FIRE. (See TC 3-21.60 for hand and arm signals.)

Prearranged Signals

C-86. Prearranged signals are either visual or sound signals such as casualty-producing devices (rifle or claymore), pyrotechnics, whistle blasts, or tracers. These signals should be included in SOPs. If leaders want to shift fire at a certain time, they give a prearranged signal such as obscurants or pyrotechnics. Upon seeing the signal, the gunner shifts fire to a prearranged point.

Personal Contact

C-87. In many situations, leaders must issue orders directly to individual Soldiers. Personal contact is used more than other methods by Infantry rifle leaders. Leaders must use maximum cover and concealment to keep from disclosing the position or themselves.

Standard Range Cards

C-88. When using the standard range card method of fire control, leaders must ensure all standard range cards are current and accurate. Once this is accomplished, leaders may designate certain targets for certain weapons with the use of limiting stakes or with fire commands. They also should designate no-fire zones or restricted fire areas to others. The vital factor in this method of fire control is gunners must be well disciplined and pay attention to detail.

Standard Operating Procedures

C-89. SOPs are actions to be executed without command developed during the training of the squads. Their use eliminates many commands and simplifies the leader’s fire control. SOPs for certain actions and commands can be developed to make gunners effective. Some examples follow:

Observation. The gunners continuously observe their sectors.
Fire. Gunners open fire without command on appropriate targets appearing within their sectors.
Check. While firing, the gunners periodically check with the leader for instructions.
Return fire. The gunners return enemy fire without order, concentrating on enemy automatic weapons.
Shift fire. Gunners shift their fires without command when more dangerous targets appear.
Rate of fire. When gunners engage a target, they initially fire at the rate necessary to gain and maintain fire superiority.
Mutual support. When two or more gunners are engaging the same target and one stops firing, the other increases the rate of fire and covers the entire target. When only one gunner is required to engage a target and the leader has alerted two or more, the gunner not firing aims on the target and follows the movements of the target. The gunner does this to fire instantly in case the other machine gun malfunctions or ceases fire before the target has been eliminated.

Fire Commands

C-90. A fire command is given to deliver fire on a target quickly and without confusion. When leaders decide to engage a target not obvious to the squad, they must provide it with the information needed to engage the target. Leaders must alert the Soldiers; give a target direction, description, and range; name the method of fire; and give the command to fire. There are initial fire commands and subsequent fire commands.

C-91. It is essential the commands delivered by the weapons squad leader, are understood, and echoed by the assistant gunner or gun team leader and gunner. Table C-5 provides an example of the weapons squad fire commands and actions taken by the weapons squad leader, assistant gunner, gun team leader, and gunner.

Table C-5. Weapons squad fire commands and actions

Initial Fire Commands

C-92. Initial fire commands are given to adjust onto the target, change the rate of fire after a fire mission is in progress, interrupt fire, or terminate the alert. Commands for all direct-fire weapons follow a pattern including similar elements. There are six elements in the fire command of the machine gun: alert; direction; description; range; method of fire; and command to open fire. The gunners repeat each element of fire command as it is given.

Alert

C-93. This element prepares the gunners for more instructions. Platoon leaders may alert both gunners in the squad and may have only one fire, depending upon the situation. To alert and have both gunners fire, leaders announce FIRE MISSION. If they desire to alert both gunners but have only one fire, they announce GUN NUMBER ONE, FIRE MISSION. In all cases, upon receiving the alert, the gunners load their machine guns and place them on fire.

Description

C-94. The target description creates a picture of the target in the gunners’ minds. To properly apply their fire, the Soldiers must know the type of target they are to engage. Leaders should describe it briefly. If the target is obvious, no description is necessary.

Direction

C-95. This element indicates the general direction to the target. It may be given in one or a combination of the following methods.

C-96. Oral. The leader orally gives the direction to the target in relation to the position of the gunner. For example, FRONT, LEFT FRONT, or RIGHT FRONT.

C-97. Pointing. Leaders designate a small or obscure target by pointing with their finger or aiming with a weapon. When they point with their finger, a Soldier standing behind them should be able to look over their shoulder and sight along their arm and index finger to locate the target. When aiming the weapon at a target, a Soldier looking through the sights should be able to see the target. Leaders also may use lasers in conjunction with night vision devices to designate a target to the gunner.

C-98. Tracer ammunition. Tracer ammunition is a quick and sure method of designating a target not clearly visible. When using this method, leaders first should give the general direction to direct the gunner’s attention to the target area. To prevent the loss of surprise when using tracer ammunition, leaders do not fire until they have given all elements of the fire command except the command to fire. Leaders may fire their individual weapon. The firing of the tracers then becomes the last element of the fire command, and it is the signal to open fire.

CAUTION
Soldiers must be aware night vision devices, temporary blindness (“white out”) may occur when firing tracer ammunition at night or when exposed to other external light sources. Lens covers may reduce this effect.

C-99. Reference points. Another way to designate obscure targets is to use easy-to-recognize reference points. All leaders and gunners must know terrain features and terminology used to describe them. (See TC 3-25.26 for additional information.) When using a reference point, the word “reference” precedes its description. This is done to avoid confusion. The general direction to the reference point should be given.

Range

C-100. Leaders always announce the estimated range to the target. The range is given, so the gunner knows how far to look for the target and what range setting to put on the rear sight. Range is announced in meters. However, since the meter is the standard unit of range measurement, the word “meters” is not used. With machine guns, the range is determined and announced to the nearest hundred or thousand example, THREE HUNDRED, or ONE THOUSAND.

Method of Fire

C-101. This element includes manipulation and rate of fire. Manipulation dictates the class of fire with respect to the weapon. It is announced as FIXED, TRAVERSE, SEARCH, or TRAVERSE AND SEARCH. (See paragraphs C-31 to C-37.) Rate controls the volume of fire (sustained, rapid, and cyclic). Normally, the gunner uses the sustained rate of fire. When a sustain rate of fire is to be used, rate of fire is omitted from the fire command. The method of fire of the machine gun is usually 3- to 5-round bursts (M249) and 6- to 9-round bursts (M240-series).

Command to Open Fire

C-102. When fire is to be withheld so surprise fire can be delivered on a target or to ensure both gunners open fire at the same time, leaders may preface the command to commence firing with AT MY COMMAND or AT MY SIGNAL. When the gunners are ready to engage the target, they report READY to the leader. The leader then gives the command FIRE at the specific time desired. If immediate fire is required, the command FIRE is given without pause and gunners fire as soon as they are ready.

Subsequent Fire Commands

C-103. Subsequent fire commands are used to make adjustments in direction and elevation, to change rates of fire after a fire mission is in progress, to interrupt fires, or to terminate the alert. If the gunner fails to engage a target properly, the leader must correct the gunner promptly by announcing or signaling the desired changes. When these changes are given, the gunner makes the corrections and resumes firing without further command.

C-104. Adjustments in direction and elevation with the machine gun always are given in meters one finger is used to indicate 1 meter and so on. Adjustment for direction is given first. Example: RIGHT ONE ZERO METERS or LEFT FIVE METERS. Adjustment for elevation is given next. Example: ADD FIVE METERS or DROP ONE FIVE METERS. These changes may be given orally or with hand and arm signals:

Changes in the rate of fire are given orally or by hand and arm signals.
To interrupt firing, the leader announces CEASE FIRE, or the leader signals to cease fire. The gunners remain on the alert. They resume firing when given the command FIRE.
To terminate the alert, the leader announces CEASE FIRE, END OF MISSION.

Doubtful Elements And Corrections

C-105. When gunners are in doubt about elements of fire commands, they reply, SAY AGAIN RANGE, TARGET. Leaders then announces THE COMMAND WAS, repeats the element in question, and continues with the fire command.

C-106. When leaders make an error in the initial fire command, they correct it by announcing CORRECTION, and gives the corrected element. When leaders make an error in the subsequent fire command, they may correct it by announcing CORRECTION. They then repeat the entire subsequent fire command.

Abbreviated Fire Commands

C-107. Fire commands do not need be complete to be effective. In combat, leaders give only the elements necessary to place fire on a target quickly and without confusion. During training, however, they should use all the elements to get gunners in the habit of thinking and reacting properly when a target is to be engaged. After the gunner’s initial training in fire commands, the gunner should be taught to react to abbreviated fire commands, using one of the following methods.

Oral

C-108. When leaders want to place the fire of one machine gun on an enemy machine gun, they may want to use oral commands. For example, leaders can quickly tell the gunner to fire on an enemy gun.

Hand and Arm Signals

C-109. Battlefield noise and distance between the gunners and leaders often make it necessary to use hand and arm signals to control fire (see figure C-19 on page C-32). When an action or movement is to be executed by only one of the gunners, a preliminary signal is given to the gunner only. The following are commonly used signals for fire control:

Ready. Gunners indicate they are ready to fire by yelling UP or having the assistant gunner raise the hand above the head toward the leader.
Commence firing or change rate of firing. Leaders bring their hand (palm down) to the front of their body about waist level and moves it horizontally in front of the body. To signal an increase in the rate of fire, they increase the speed of the hand movement. To signal slower fire, they decrease the speed of the hand movement.
Change direction or elevation. Leaders extend their arm and hand in the new direction and indicates the amount of change necessary by the number of fingers extended. The fingers must be spread so gunners can easily see the number of fingers extended. Each finger indicates 1 meter of change of the weapon. If the desired change is more than 5 meters, leaders extend their hand the number of times necessary to indicate the total amount of change. For example, right nine would be indicated by extending the hand once with five fingers showing and a second time with four fingers showing for a total of nine fingers.
Interrupt or cease firing. Leaders raise their hand and arm (palm outward) in front of their forehead and brings it downward sharply.
Other signals. Leaders can devise other signals to control their weapons. A detailed description of hand and arm signals is given in TC 3-21.60.

Figure C-19. Hand and arm signals

Machine Gun Use

C-110. Despite their post-Civil War development, modern machine guns did not exhibit their full potential in battle until World War I. Although the machine gun has changed, the role of the machine gun and machine gunner has not. The mission of machine guns in battle is to deliver fires when and where leaders want them in both the offense and defense. Machine guns rarely, if ever, have independent missions. Instead, they provide their unit with accurate, heavy fires to accomplish the mission.

Tactical Organizations Of The Machine Gun

C-111. The accomplishment of the platoon’s or squad’s mission demands efficient and effective machine gun crews. Leaders consider the mission and organize machine guns to deliver firepower and direct fire support to area(s) or point(s) needed to accomplish the assigned mission.

C-112. Infantry rifle platoons have an organic weapons squad consisting of a weapons squad leader, two-Javelin teams (see appendix D), and two-medium machine gun teams. (See chapter 1 for additional information on weapons squad.) Depending on the platoon’s or squad’s mission, there could be additional machine gun teams attached to the platoon or squad.

C-113. The medium machine gun team has a gunner, assistant gunner, and ammunition bearer. In some units the senior member of the gun team is the gunner. In other units the assistant gunner is the senior gun team member who also serves as the gun team leader.

C-114. Table C-6 illustrates equipment carried by the weapons squad. Table C-7 on page C-34 illustrates the duty positions within the weapons squad and gives possible duty descriptions and responsibilities. The table shows possible position and equipment use only. Individual unit SOPs and available equipment dictate the exact role each weapons squad member plays within the squad.

Note. See appendix D for information on the Javelin (and when replaced with the M3 Multi-role, Antiarmor, Antipersonnel Weapon System [known as MAAWS]) teams in the weapons squad.

Table C-6. Weapons squad equipment by position, example

Table C-7. Weapons squad duty positions and responsibilities

Security

C-115. Security includes all command measures to protect against surprise, observation, and annoyance by the enemy. The gun team is responsible for its immediate local security, specifically provided by the assistant gunner and/or ammunition bearer for close in local security to the gunner, who is fixated on deeper targets. Though the principal unit security measures against ground forces include employment of observation posts, security patrols, and detachments covering the front flanks and rear of the unit’s most valuable weapons systems and vulnerable areas. The composition and strength of these detachments depends on the size of the main body, its mission, and nature of the opposition expected. The presence of machine guns with security detachments augments their firepower to delay, attack, and defend, by virtue of inherent firepower.

C-116. The potential of air and ground attacks on the unit demands every possible precaution for maximum security while on the move. Where this situation exists, the machine gun crew must be thoroughly trained in the hasty delivery of antiaircraft fire and of counterfire against enemy ground forces. The distribution of the medium machine guns in the formation is critical. The medium machine gun crew is constantly on the alert, particularly at halts, ready to deliver fire as soon as possible. If leaders expect a halt to exceed a brief period, they carefully choose medium machine gun positions to avoid unduly tiring the medium machine gun crew. If they expect the halt to extend for a long period, they can have the medium machine gun crew take up positions in support of the unit. The crew covers the direction from which they expect enemy activity as well as the direction from which the unit came. Leaders select positions permitting the delivery of fire in the most probable direction of enemy attack, such as valleys, draws, ridges, and spurs. They choose positions offering obstructed fire from potential enemy locations.

Employment Of Fire And Movement

C-117. The employment of fire and movement is essential and greatly depends upon the other during maneuver. Without the support of covering fires, maneuvering in the presence of enemy fire can result in disastrous losses. Covering fires, especially providing fire superiority, allow maneuvering in the offense. However, fire superiority alone rarely wins battles. The primary objective of the offense is to advance, occupy, and hold the enemy position.

Machine Gun as a Base of Fire

C-118. Machine gun fire from a support by fire position must be the minimum possible to keep the enemy from returning fire. Ammunition must be conserved so the guns do not run out of ammunition.

C-119. The weapons squad leader positions and controls the fires of all medium machine guns in the element. Machine gun targets include essential enemy weapons or groups of enemy targets either on the objective or attempting to reinforce or counterattack. In terms of engagement ranges, medium machine guns in the base-of-fire element may find themselves firing at targets within a range of 800 meters. The nature of the terrain, desire to achieve some standoff, and the mission variables of METT-TC (I) mission, enemy, terrain and weather, troops and support available, time available, civil considerations, and informational considerations prompt the leader to the correct tactical positioning of the base-of-fire element.

C-120. The medium machine gun quickly delivers an accurate, high-volume rate of lethal fire on large areas. When accurately placed on the enemy position, medium machine gun fires can achieve fire superiority for duration of the firing. Troops advancing in the attack should take full advantage of this period to maneuver to a favorable position from where they can facilitate the last push against the enemy. In addition to creating enemy casualties, medium machine gun fire destroys the enemy’s confidence and neutralizes their ability to engage the friendly maneuver element.

C-121. All vocal commands from the leaders to change the rates of fire are accompanied simultaneously by hand and arm signals. There are distinct phases of rates of fire employed by the base-of-fire element:

Initial heavy volume (rapid rate) to gain fire superiority.
Slower rate to conserve ammunition (sustained rate) while still preventing return fire as the assault moves forward.
Increased rate as the assault nears the objective.
Shift fires (commonly called walking fires) forward of the assault line.
Lift and/or shift to other targets or targets of opportunity.

C-122. Machine guns in the support by fire role should be set in and assigned a primary and secondary sector of fire as well as a primary and alternate position. They are suppressive fire weapons used to suppress known and suspected enemy positions. Therefore, gunners cannot be allowed to empty all their ammunition into one bunker simply because it is all they can identify at the time.

C-123. The support by fire position, not the assault element, is responsible for ensuring there is no masking of fires. The assault element might have to mask the support by fire line because it has no choice on how to move. It is the support by fire gunner’s job to shift fires continually or move gun teams or the weapons squad to support the assault and prevent masking.

C-124. Shift and shut down the weapons squad gun teams one at a time, not all at once. M320 and mortar or other indirect fire can be used to suppress while the medium machine guns are moved to where they can fire.

C-125. Leaders must consider the surface danger zones of the machine guns when planning and executing the lift and/or shift of the support by fire guns. The effectiveness of the enemy on the objective will play a large role in how much risk should be taken with respect to the lifting or shifting of fires. Once the support by fire line is masked by the assault element, fires are shifted and/or lifted to prevent enemy withdrawal or reinforcement.

Machine Gun with the Maneuver Element

C-126. The medium machine guns seldom accompany the maneuver element. The gun’s primary mission is to provide covering fire. The medium machine guns only are employed with the maneuver element when the AO assigned to the assault, platoon, squad, or company is too narrow to permit proper control of the guns. The medium machine guns then are moved with the unit and readied to employ on order from the leader and in the direction needing the supporting fire.

C-127. When medium machine guns move with the element undertaking the assault, the maneuver element brings the medium machine guns to provide additional firepower. These weapons are fired from a bipod, in an assault mode, from the hip, or from the underarm position. They target enemy automatic weapons anywhere on the unit’s objective. Once the enemy’s automatic weapons have been destroyed (if any), the gunners distribute their fire over their assigned sector. In terms of engagement ranges, the medium machine gun in the assault engages within 300 meters of its target and frequently at point-blank ranges.

C-128. Where the AO is too wide to allow proper coverage by the platoon’s organic medium machine guns, the platoon or squads can be assigned additional medium machine guns or personnel from within the company. This may permit the platoon or squads to accomplish its assigned mission. The medium machine guns are assigned a sector to cover and move with the maneuver element.

Machine Guns In The Offense

C-129. In the offense, the platoon leaders have the option to establish their base-of-fire element with one or two medium machine guns, the M249 light machine gun, the M320 weapon system, or a combination of the weapons. The platoon sergeant or weapons squad leader may position this element and control its fires when the platoon scheme of maneuver is to conduct the assault with the Infantry squads.

M249 Light Machine Gun In The Offense

C-130. In the offense, M249s target enemy-supporting weapons and can be fired from fixed positions anywhere on the squad’s objective. When the enemy’s supporting weapons have been destroyed, or if there are none, the machine gunners distribute their fire over the portion of the objective corresponding to their team’s position.

M240-Series Medium Machine Guns in the Offense

C-131. In the offense, the M240-series machine gun, when placed on a tripod, provides stability and accuracy at greater ranges than the bipod, but it takes more time to maneuver the machine gun should the need arise. The machine gunners target essential enemy weapons until the assault element masks their fires. They also can be used to suppress the enemy’s ability to return accurate fire, or to hamper the maneuver of the enemy’s assault element. They fix the enemy in position and isolate by cutting off their avenues of reinforcement. They then shift their fires to the flank opposite the one being assaulted and continue to target automatic weapons providing enemy support and engage enemy counterattack. M240-series fires also can be used to cover the gap created between the forward element of the friendly assaulting force and terrain covered by indirect fires when the indirect fires are lifted and shifted. On signal, the machine gunners and base-of-fire element displace to join the assault element on the objective.

Machine Guns In The Defense

C-132. The platoon’s defense centers on its machine guns. The medium machine gun is the base for the defense, they are planned first, around a PDF or FPL, and then other planned targets within the primary sector of fire. They engage targets in secondary sector of fire when not firing the primary sector, and, when necessary, transition to the FPL. Machine gun teams are also prepared to fire in support of the unit’s counterattack. Platoon leaders site the rifle squad to protect the machine guns against the assault of a dismounted enemy formation. The machine gun provides the necessary range and volume of fire to cover the squad’s front in the defense.

C-133. The primary requirement of a suitable machine gun position in the defense is its effectiveness in accomplishing specific missions. The position should be accessible and afford cover and concealment. Machine guns are sited to protect the front, flanks, and rear of occupied portions of defensive positions, and to be mutually supporting. Attacking troops usually seek easily traveled ground providing cover from fire. Every machine gun should have three positions: primary, alternate, and supplementary. Each of these positions should be chosen by leaders to ensure their sector is covered and machine guns are protected on their flanks.

C-134. Leaders site the machine gun to cover the entire sector or to overlap sectors with the other machine guns. The engagement range may extend from more than 1,000 meters where the enemy begins the assault to point-blank range. Machine gun targets include enemy automatic weapons and command and control elements.

C-135. Machine gun fire is distributed in width and depth in a defensive position. Leader can use machine guns to subject the enemy to increasingly devastating fire from the initial phases of the attack, and to neutralize partial successes the enemy might attain by delivering intense fires in support of counterattacks. The machine gun’s tremendous firepower enables the unit to hold ground. This is what makes it the backbone or framework of the defense.

M249 Light Machine Gun in the Defense

C-136. In the defense, the M249 adds increased firepower without the addition of manpower. Characteristically, M249s are light, fire rapidly, and have more ammunition than the rifles in the squad they support. Under certain circumstances, the platoon leader may designate the M249 machine gun as a platoon crew-served weapon.

M240-Series Medium Machine Guns in the Defense

C-137. In the defense, the medium machine gun provides sustained direct fires covering the most likely or most dangerous enemy dismounted avenues of approach. It protects friendly units against the enemy’s dismounted close assault. Platoon leaders position their machine guns to concentrate fires in locations where they want to inflict the most damage to the enemy. Leaders also place them where they can take advantage of grazing enfilade fires, stand-off or maximum engagement range, and best observation of the target area. Machine guns provide overlapping and interlocking fires with adjacent units and cover tactical and protective obstacles with traversing or searching fires. When FPFs are called for, machine guns (aided by M249 fires) place a barrier of fixed, direct fire across the platoon or squad front. Leaders position machine guns to—

Concentrate fires where they want to kill the enemy.
Fire across the platoon and squad front.
Cover obstacles by direct fire.
Tie in with adjacent units.

Ammunition Planning

C-138. Leaders must carefully plan the rates of fire to be employed by machine guns as they relate to the mission and amount of ammunition available. The weapons squad leader must understand fully the mission the amount of available ammunition and application of machine gun fire needed to support fully all vital events of the mission. Planning ensures the guns do not run out of ammunition.

C-139. A mounted platoon or squad might have access to enough machine gun ammunition to support the guns throughout its operation. A dismounted platoon or squad with limited resupply capabilities must plan for only the basic load to be available. In either case, leaders must consider vital events the guns must support during the mission. They must plan the rate of machine gun fire needed to support the vital events, and amount of ammunition needed for scheduled rates of fire.

C-140. Leaders must make an estimate of the total amount of ammunition needed to support all the machine guns. They then must adjust the amount of ammunition used for each event to ensure enough ammunition is available for all phases of the operation. Because medium machine guns may see different parts of the battlefield, their expenditure rates will vary. The weapons squad leader must monitor ammunition consumption to ensure rates are not too high, and cross-level ammunition between gun teams as necessary. Examples of planning rates of fire and ammunition requirements for a platoon or weapons squad’s machine guns in the attack follow.

Know Rates of Fire

C-141. Leaders and gunners must know how much ammunition is required to support the different rates of fire each platoon or weapons squad machine gun and assault weapon will require. Coupling this knowledge with an accurate estimate of the length of time and rates of fire their guns are scheduled to fire will ensure enough ammunition resources to cover the entire mission. As part of an example of the planning needed to use M240-series in support by fire roles, the rates of fire of the M240-series are listed in table C-8 on page C-40.

Table C-8. M240-series rates of fire

Ammunition Requirement

C-142. Leaders must calculate the number of rounds needed to support every machine gun throughout all phases of the operation. Ammunition must be allocated for each vital event and to support movement with suppressive fires. Additional amounts of ammunition, when required, are carried/distributed (for example, every Soldier may be required to carry an extra 100 rounds for the guns) across the platoon or pre-stocked in the defense.

Next Page : Appendix D – Shoulder-Launched Munitions and Close Combat Missile System