CALL Newsletter No. 99-16: Urban Combat Operations; Appendix C: Weapon Effects and

APPENDIX C

Weapons Effects and Employment
in an Urban Environment
by Tactics Group, The Basic School (USMC),
MCCDC, Quantico, Va.

As with any other type of operation, a unit leader plans to use all available weapon systems: organic, supporting, and attached. The three-dimensional and naturally restrictive nature of urban terrain requires that every weapons system be employed to maximize its effects. Weapons should be employed to create and/or exploit tactical advantages. Street patterns and building location influence the plan of attack or defense by creating "city canyons" which are compartmentalized portions of the area. City street width, line of sight distances, and intervisibility problems caused by building angles can all influence the selection of firing positions and the effectiveness of weapons. Buildings that may mask fires, key terrain, critical areas, and building construction should also be considered when deciding how to employ weapons. Below are some of the effects of and employment considerations for weapons in an urban environment.

1. WEAPONS EFFECTS.

Obviously, unit leaders will have to take into consideration the effects of the specific weapons under their direct control and those they may bring to bear in the urban setting. This will vary and will be influenced by availability, logistics, effectiveness, and suitability as they apply to the current situation faced by that leader. Below are some general considerations concerning the effectiveness of weapons in the urban environment.

(1) Hard, smooth, and flat surfaces are characteristic of urban targets. Rounds usually strike these surfaces at some degree of obliquity. This reduces the effectiveness of the round and increases the chance of ricochets. In addition, the above also means that up to 25 percent of impact-fused explosive rounds (i.e., 40-mm grenades) will not detonate when striking such targets at an angle.

(2) Engagement ranges in urban combat are close. Historically, about 90 percent of all engagements occur at 50 meters or less. Minimum arming ranges and unit safety from backblast or fragmentation must be considered.

(3) Because of the close nature of most engagements and the broken nature of the urban terrain, the time available to engage targets will be short. Riflemen have difficulty engaging with deliberate, well-aimed shots without prolonged exposure to enemy observation and fire.

(4) Depression and elevation limits for some weapons create dead space. Tall buildings form deep canyons and make engaging targets in the upper portions of these buildings difficult or impossible with such weapons. Positions that have depression limits may not be able to engage enemy positions in basement or cellar positions.

(5) Smoke from burning buildings, dust created by explosions, shadows from buildings, and lack of ambient light penetrating inner rooms all contribute to reduce visibility. Targets, even at close range, may be difficult to see. The effectiveness of night-vision goggles and even thermal sights may be greatly reduced.

(6) Specific rounds and munitions must be evaluated for their effects against and penetration of certain types of building construction when planning. This will reduce the possibility of friendly fire injuries. In addition, leaders must evaluate the risk of starting fires. The benefits of using tracer ammunition, which can be shot from a number of different weapons systems, must be evaluated against the likelihood and consequences of starting fires.

(7) The presence of power lines must be considered when employing wire-guided missiles. Guidance wires that cross "hot" power lines can short out and cause the missile to become erratic.

(8) Modern engineering and design improvements mean that most large buildings constructed since World War II are resilient to the blast effects of demolition and artillery attacks. Even though portions may be rubbled or burned, buildings may hold their structural integrity.

(9) Understanding the effects of different types of weapons can also have an effect on defenses and the type of protection constructed or used. Many materials normally found in an urban environment can be used to effectively protect against modern weapons and their effects. Furniture and building materials taken from interior walls can be fashioned into overhead cover to protect from the effects of artillery, mortar, or demolition attacks. Chain-link fences can be placed in front of fighting positions to protect against rocket-propelled grenades (RPGs) and other shaped-charge warhead weapons. Sandbags are very effective against small arms fire, but may be limited in supply. Some effective alternatives to sandbags may be furniture, vehicle bodies, 55-gallon drums filled with water, or brick/cement rubble between boards. However, a disadvantage to the latter is the possibility of secondary fragmentation.

(10) The depleted uranium (DU) used in the APDS (SABOT) tank round poses a significant health hazard to noncombatants and will for a long time after it is used in an urban combat situation. This long-term health hazard is due to radiation effects of the penetrator.

2. WEAPONS EMPLOYMENT.

The following are some employment considerations as they pertain to specific weapons normally found at the rifle company or platoon level.

(1) M16A2 Service Rifle. Rifles are the primary weapon to engage and kill the enemy in MOUT. In addition, rifles are particularly effective in suppressing enemy positions placed in individual windows and doors of buildings because of their ability to deliver accurate fire. To effectively engage small, fleeting targets requires a high degree of accuracy and weapons fired in the semiautomatic mode. Tracer ammunition may be used (after considering building construction and the risk of fires) by unit leaders to direct the fire of their units. Penetration of the 5.56 round is optimal at 200 meters. Because of the close nature of most engagements in urban areas, this penetration will be reduced. The 5.56 round, however, will easily penetrate materials commonly found on the interior of buildings (wooden doors, paneling, Sheetrock, or plaster). The 5.56 round will not penetrate brick and other masonry works initially, but successive rounds may.

(2) M249 Squad Automatic Weapon. SAWs should be employed using the same considerations as M16A2s. The penetration capabilities and limitations of the 5.56 rounds are the same. The SAW, however, provides a much greater volume of fire and is, therefore, well suited for suppression of enemy positions and can be utilized to isolate or suppress objectives. The increased rate of fire will also have a corresponding greater destructive effect on buildings and building materials. SAWs are cumbersome in the assault because of their length and weight. This does not mean that they will not participate in the clearing of buildings; rather, they should be placed in a covering team or security team while clearing rooms.

TYPE	PENETRATION	ROUNDS (REQUIRED)
8 inch reinforced concrete	Initial Loophole	35 250
14 inch triple brick	Initial Loophole	90 160
12 inch cinder block with single brick veneer	Loophole Breach hole	60 250
9 inch double brick	Initial Loophole	70 120
16 inch tree trunk or log wall	Initial	1 to 3
12 inch cinder block (filled with sand)	Loophole	35
24 inch double sandbag wall	Initial	220
3/8 inch mild steel door	Initial	1

Initial = penetration only, no loophole
Loophole = penetration about 7 inches in diameter
Breach hole = large enough for a man to enter

Table 1. Structure penetration capabilities of the 5.56mm round against typical urban targets (range 25 to 100 meters).

(3) M203 Grenade Launcher. The M203 can be effective at destroying point targets in the offense or defense. The destructive force of the 40-mm HE or HEDP rounds can be a significant combat multiplier in urban combat. Blast effects and fragmentation within enclosed rooms may be amplified. In addition, the fragmentation effects may be multiplied by the added fragmentation created by building materials (masonry chips, wood splinters, etc.). Because of the close nature of combat in urban areas, care must be taken to avoid friendly forces being affected by fragmentation, and attention must be paid to minimum arming distances of the rounds. Another consideration is interior wall construction. M203 rounds may pass right through light building materials like Sheetrock or paneling without detonating. The array of M203 rounds make it a good weapon for delivering covering smoke, signals, illumination, and CS. Because of the trajectory of the round, the M203 round can be delivered into defilade such as behind walls, piles of rubble, or buildings. M203 gunners should be proficient enough to deliver fire through windows, doors, and small openings.

TARGET	PENETRATION (inches)
Sandbags	20 (double layer)
Sand-filled cinder block	16
Pine logs	12
Armor plate	2

Table 2. Penetration capabilities of 40mm HEDP round.

(4) M240G Machine-Gun. The M240G is the rifle company's primary organic direct fire weapon used to suppress designated targets/areas, isolate objectives, or establish kill zones down streets and alleys. Employment in the offense and defense are the same as any other environment with some special considerations. Streets, alleys, and open areas normally found in an urban environment provide an opportunity to achieve grazing fire seldom equaled in other types of terrain. To achieve maximum grazing fires, machine-guns should be positioned on the lower levels, in basements, or cellar firing positions. However, rolling urban terrain, buildings, rubble, vehicles, and other objects may all present obstacles to machine-gun fire and require them to be positioned higher within buildings. The M240G is a cumbersome weapon, making it difficult to use while clearing a building. The weapon can be fired from the assault fire position using the bipods, or employed on the M122 tripod for increased accuracy and stability. The penetration capability of the 7.62 round, however, penetrates most light construction materials easily and will penetrate most typical urban walls with continued and concentrated fire. It will not penetrate steel-reinforced concrete and dense natural stone structures.

RANGE (meters)	PINE BOARD (inches)	DRY LOOSE SAND (inches)	CINDER BLOCK (inches)	CONCRETE (inches)
25	13	5	8	2
100	18	4.5	10	2
200	41	7	8	2

Table 3a. Penetration capabilities of a single 7.62mm (ball) round.

TYPE	THICKNESS (inches)	HOLE DIAMETER (inches)	ROUNDS REQUIRED
Reinforced concrete	8	7 (loophole)	100
Triple brick wall	14	7 (loophole)	170
Concrete block with single brick veneer	12	6 and 24	30 and 200
Cinder block (filled)	12	Initial	18
Double brick wall	9	Initial	45
Double sandbag wall	24	Initial	110
Log wall	16	Initial	1
Mild steel door	3/8	Initial	1

Initial = penetration only, no loophole
Loophole = penetration about 7 inches in diameter

Table 3b. Structure penetrating capabilities of 7.62mm round (NATO ball) against typical urban targets (range 25 meters).

(5) Heavy Machine-guns - M2 .50-cal/MK-19. Heavy machine-guns are often employed on their vehicular mount both in the offense and defense. If necessary, they can be mounted on the M3 tripod for use in the ground role or in upper levels of buildings. As with the M240G, the obstacle that will affect the employment of heavy machine-guns will be the limited availability of long-range fields of fire. Additionally, grazing fire of the M2 .50-cal machine-gun may be obstructed by rubble. The .50-cal machine-gun's ammunition penetration will be affected by the shorter ranges, but not as much as that of the M240G. The .50-cal machine-gun is capable of producing significant amounts of damage to structures with continued, concentrated fires. The MK-19 40-mm automatic grenade launcher is capable of delivering large volumes of 40-mm grenade fire into defilade, behind rubble, and into buildings. It is also capable of producing significant damage to buildings. The MK-19 may be affected by the short engagement distances, and the minimum arming distance of the rounds should be considered. Also, as previously mentioned, as much as 25 percent of the rounds fired from the MK-19 may skip or ricochet off hard surfaces without detonating.

TYPE	THICKNESS (inches)	HOLE DIAMETER (inches)	ROUNDS REQUIRED
Reinforced concrete	10 18	12 24 7	50 100 140
Triple brick wall	12	8 26	15 20
Concrete block with single brick veneer	12	10 33	25 45
Armor plate	1	Initial	1
Double sandbag wall	24	Initial	5
Log wall	16	Initial	1

Initial = penetration only, no loophole

Table 4a. Structure penetrating capabilities of .50 caliber ball against typical urban targets (range 35 meters).

THICKNESS (meters)	100 METERS (rounds)	200 METERS (rounds)
2	300	1,200
3	450	1,800
4	600	2,400

Table 4b. Number of rounds needed (.50 caliber) to penetrate a reinforced concrete wall at a 25 degree obliquity.

NOTE: For statistics on the MK-19, see Table 2.

(6) Rocket Launchers and Anti-Tank Guided Missiles (ATGM). The M136 AT-4 and MK 153 SMAW (USMC) are the primary rocket launchers that will support a rifle company in MOUT. Javelins or TOWs may also support a company. These will be used to destroy enemy fortifications and light armored vehicles. AT-4s and SMAWS are extremely effective at destroying enemy positions within buildings. To maximize their effectiveness, they should generally be aimed beside or at the base of the intended target opening (window or door). If shot directly into the opening, the warhead may detonate behind the enemy or pass through interior walls, both of which will lessen the fragmentation effect of the round. When exploded next to the opening, the blast effect directly on the other side of the wall is magnified by the fragmentation produced from the construction materials themselves (concrete, brick, or wood splinters). SMAWs are also capable of creating man-sized breaches in exterior walls of most buildings. It will be least effective in this role against steel-reinforced concrete and heavy natural stone walls. Regardless of the type, most masonry walls may require successive shots to create a man-sized hole. Javelin and TOWs are normally employed in a conventional role to cover likely mechanized avenues of approach and to destroy specific point targets during the attack or defense. Because of their shaped charge warheads, they will be less effective at creating large holes in structure walls, and the fragmentation created is limited. Much research has been done concerning the backblast of these types of weapons in MOUT.

Since the end of World War II, the U.S. Army has conducted extensive testing on the effects of firing recoilless weapons from within enclosures. The following were some of the findings of this testing:

(a) Generally, it has been found that the backblast created offers minimal danger to the gunners, even in enclosed positions. However, hearing loss is still a serious hazard that can be expected. This must be evaluated against the advantage gained in combat from firing from cover.

(b) Damage to the room and/or structural integrity of the building can be reduced by ensuring adequate ventilation (open window and/or door).

(c) Consideration should be given to other occupants of the building. The safest place for other soldiers in the room with the firer is against the wall from which the weapon is fired. Backblast, plastic ignition plugs, and flying debris are a deadly hazard to anyone standing directly behind a recoilless weapon when it is fired. More significant is the danger created by backblast when fired outside in MOUT. Streets and alleys tend to canalize the backblast effects. Dust, debris, and other objects created from urban warfare will also become problematic as they are kicked up and blown around by the backblast. Thermal sites on the Javelin and TOW may be of great use even during the day because of their ability to observe through smoke and dust.

(d) Minimum arming distances will be another consideration to take into account. To ensure sufficient distance is provided to allow the warhead to arm itself, rocket launchers and ATGMs may need to be placed in the upper levels of buildings or on rooftops. Shooting down from these positions will also be more effective against armored vehicles.

(7) Mortars. Mortars are a high-trajectory weapon. This makes them well suited for urban combat due to the height of buildings and the natural "canyons" they create. Mortars can be employed against enemy positions on rooftops, behind buildings, or in other defilade positions. Mortars can be used to fix enemy positions, isolate objectives, suppress, and destroy enemy positions or formations in the open. Suppressing enemy positions within buildings may be difficult or impossible due to building construction. Conversely, mortars may penetrate the rooftop or cause significant structural damage to lightly constructed buildings. To deny the enemy rooftop positions or limit the amount of rubble produced, HE/VT may be used. A major drawback is the ability of the unit calling for fire to observe the mortar fire which may be reduced due to buildings or rubble.

(8) Armor/Mechanized assets. In the offense, mechanized assets may be used to isolate the objective, destroy point targets, or suppress enemy positions. Tanks, Bradleys, M113s, AAVs (USMC), and LAVs (USMC) are extremely lethal in a direct fire role against enemy armored vehicles and fortified positions. The capabilities and limitations associated with armor and mechanized assets remain the same in MOUT as they do in other environments. Additional roles these assets may fill are smashing barricades, establishing mobile road blocks, acting as evacuation or civil disturbance platforms, and logistics carriers. The main armament of armor and mechanized vehicles can have devastating effects on buildings. In addition, armored vehicles also have secondary weapons (medium and heavy machine-guns) that can be used to support the attack or defense. Some mechanized assets also bring to the MOUT battlefield additional thermal sights that can be employed similar to the Javelin and TOWs. It is important to remember that with all the inherent strengths armored vehicles have, urban terrain is a very dangerous environment in which to operate. The broken nature of the terrain, elevated firing positions, and limited maneuver space can allow the enemy to get close to armored vehicles and inflict serious, if not fatal, damage. In the offense or defense, the infantry bears responsibility for protecting armored and mechanized vehicles from enemy dismounted armor-killer teams.

(9) Artillery/Naval Gunfire. Because of their relatively flat trajectory, artillery and naval gunfire are limited in their ability to suppress or destroy point targets within an urban area. Both will have difficulty hitting targets hidden within buildings or in the natural defilade created by the buildings. Use of laser-guided munitions (Copperhead) may be useful to engage targets with pinpoint accuracy, but again the masking of those fires may be a problem. Artillery and NGF can be used to isolate urban centers or areas within the built-up area. They can also be used to illuminate areas within the city. Both artillery and NGF, when fired within urban areas, will create significant amounts of rubble and will cause considerable damage to structures. This may hinder follow-on operations and should be considered. Artillery may be used in the direct fire mode to rubble buildings or create a breach point. Depending on building construction, the danger of fires started by artillery and NGF should also be considered. Rules of Engagement (ROE) may prohibit the use of these fires within all, or a portion of, the urban area.

(10) Non-lethal Weapons. Much progress has been made in recent years on development of non-lethal weapons, and research continues to be done. One reason that this subject has received so much attention has been the need for dealing with large numbers of people when deadly force was not an option or not the best option to choose first. MOUT is an area where non-lethal weapons may be of great assistance due to the large number of civilians associated with urban areas. Non-lethal weapons may be an effective way of dealing with an enemy located within a civilian population without putting civilians at risk. Even without the presence of civilians, some non-lethal weapons may be an effective way of dealing with the enemy. For example, CS gas can be delivered, by any number of ways, into a building to drive the enemy out of their positions. Pepper spray or stinger ball grenades may be substituted for fragmentary or concussion grenades when clearing a building.

3. REFERENCES.

For more detailed information concerning weapon effects and employment, refer to FM 90-10-1, An Infantryman's Guide To Combat in Built-up Areas, Chapter 8; and MCWP 3-35.3, Military Operations On Urbanized Terrain, Appendix B.

Appendix B: U.S. Marine Organization

Appendix D: Aircrew Map Conversion Techniques

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