M16 5.56mm Semiautomatic Rifle

The M16 Assault Rifle is the standard issue shoulder weapon in the US military. It marks a departure from normal ballistics in that it uses a smaller, high-velocity round (5.56 mm caliber vs. 7.62 mm). This results in a smaller and lighter weapon as well as smaller ammunition, significantly decreasing combat load.

The M-16 was effective at ranges of less than 400-460 meters, the range within which United States experiences in World War II and Korea had indicated that small arms engagements would occur. The weapon permitted the heavily burdened soldier to maintain the same degree of firepower at a reduced weight. And finally, the M-16 allowed every soldier to have an automatic fire capability whenever the situation required it, while the weapon's lighter ammunition facilitated battlefield resupply in greater quantities, enabling the resupply of field units for longer periods of time.

While the M16 possessed less "stopping power" than the M14. But it was more accurate due to the reduction in recoil stemming from the smaller proiectile fired. Both the M16Al and the AK-47 rifles were judged far more effective than the M14 in terms of expected casualties per combat load. In general, they produced two times the number of combat casualties that could be produced by the M14. Thus there was clear evidence of military utility in the M16 rifle, resulting in an increased degree of military advantage accruing to its user.

Rifle squads consist of a rifle squad leader and eight soldiers. The rifle squad leader is the senior tactical leader of the squad and controls the squad's movement and fires. He conducts squad training and maintains the squad's ability to conduct tactical missions successfully. Each infantry squad is further organized into two 4-man fire teams consisting of a team leader, a grenadier, and an automatic rifleman. The fourth member within each fire team is either the squad's antitank specialist or the squad's designated marksman. The fire team leader is a fighting leader and leads his team by example. The fire team leader controls the movement of his team and the placement of fires against enemy soldiers. He assists the squad leader as required. The infantry squad fights by fire teams and buddy teams.

Firepower is the capacity of a unit to deliver effective fires on a target. Firepower kills or suppresses the enemy in his positions, deceives the enemy, and supports maneuver. Without effective supporting fires the infantry cannot maneuver. Before attempting to maneuver, units must establish a base of fire. A base of fire is placed on an enemy force or position to reduce or eliminate the enemy's ability to interfere with friendly maneuver elements. Leaders must know how to control, mass, and combine fire with maneuver. They must identify the most critical targets quickly, direct fires onto them, and ensure that the volume of fires is sufficient to keep the enemy from returning fire effectively, and the unit from expending ammunition needlessly.

The M16A1/M16A2 rifle is the most common weapon fired in built-up areas. The M16A1/M16A2 rifle and the M249 are used to kill enemy personnel, to suppress enemy fire and observation, and to penetrate light cover. Leaders can use 5.56-mm tracer fire to designate targets for other weapons. Close combat is the predominant characteristic of urban engagements. Riflemen must be able to hit small, fleeting targets from bunker apertures, windows, and loopholes. This requires pinpoint accuracy with weapons fired in the semiautomatic mode. Killing an enemy through an 8-inch loophole at a range of 50 meters is a challenge, but one that may be common in combat in built-up areas.

When fighting inside buildings, three-round bursts or rapid semiautomatic fire should be used. To suppress defenders while entering a room, a series of rapid three-round bursts should be fired at all identified targets and likely enemy positions. This is more effective than long bursts or spraying the room with automatic fire. Soldiers should fire from an underarm or shoulder position; not from the hip. When targets reveal themselves in buildings, the most effective engagement is the quick-fire technique with the weapon up and both eyes open. Accurate quick fire not only kills enemy soldiers but also gives the attacker fire superiority.

Within built-up areas, burning debris, reduced ambient light, strong shadow patterns of varying density, and smoke all limit the effect of night vision and sighting devices. The use of aiming stakes in the defense and of the pointing technique in the offense, both using three-round bursts, are night firing skills required of all infantrymen. The individual laser aiming light can sometimes be used effectively with night vision goggles. Any soldier using NVG should be teamed with at least one soldier not wearing them.

The penetration that can be achieved with a 5.56-mm round depends on the range to the target and the type of material being fired against. The M16A2 and M249 achieve greater penetration than the older M16A1, but only at longer ranges. At close range, both weapons perform the same. Single 5.56-mm rounds are not effective against structural materials (as opposed to partitions) when fired at close range—the closer the range, the less the penetration.

For the 5.56-mm round, maximum penetration occurs at 200 meters. At ranges less then 25 meters, penetration is greatly reduced. At 10 meters, penetration by the M16 round is poor due to the tremendous stress placed on this high-speed round, which causes it to yaw upon striking a target. Stress causes the projectile to break up, and the resulting fragments are often too small to penetrate.

Even with reduced penetration at short ranges, interior walls made of thin wood paneling, sheetrock, or plaster are no protection against 5.56-mm rounds. Common office furniture such as desks and chairs cannot stop these rounds, but a layer of books 18 to 24 inches thick can. Wooden frame buildings and single cinder block walls offer little protection from 5.56-mm rounds. When clearing such structures, soldiers must ensure that friendly casualties do not result from rounds passing through walls, floors, or ceilings.

Armor-piercing rounds are slightly more effective than ball ammunition in penetrating urban targets at all ranges. They are more likely to ricochet than ball ammunition, especially when the target presents a high degree of obliquity.

The following common barriers in built-up areas stop a 5.56-mm round fired at less than 50 meters:

Although most structural materials repel single 5.56-mm rounds, continued and concentrated firing can breach some typical urban structures. The best method for breaching a masonarywall is by firing short bursts (three to five rounds) in a U-shaped pattern. The distance from the gunner to the wall should be minimized for best results—ranges as close as 25 meters are relatively safe from ricochet. Ballistic eye protection, protective vest, and helmet should be worn.

Ball ammunition and armor-piercing rounds produce almost the same results, but armor-piercing rounds are more likely to fly back at the firer. The 5.56-mm round can be used to create either a loophole (about 7 inches in diameter) or a breach hole (large enough for a man to enter). When used against reinforced concrete, the M16 rifle and M249 cannot cut the reinforcing bars.