It always was
James Fallows wrote a great history of the AR-15 way back in 1981. You should read the whole thing. It puts the lie to this notion that it’s not a weapon used for offensive purposes:
Between 1965 and 1969, more than a million American soldiers served in combat in Vietnam. One can argue that they should never have been sent there, but no one would argue that, once committed to battle, they should have been given inferior equipment. Yet that is what happened. During those years, in which more than 40,000 American soldiers were killed by hostile fire and more than 250,000 wounded, American troops in Vietnam were equipped with a rifle that their superiors knew would fail when put to the test.
The rifle was known as the M-16; it was a replacement for the M-14, a heavier weapon, which was the previous standard. The M-16, was a brilliant technical success in its early models, but was perverted by bureaucratic pressures into a weapon that betrayed its users in Vietnam. By the middle of 1967, when the M-16 had been in combat for about a year and a half, a sufficient number of soldiers had written to their parents about their unreliable equipment and a sufficient number of parents had sent those letters to their congressmen to attract the attention of the House Armed Services Committee, which formed an investigating subcommittee. The subcommittee, headed by Representative Ichord, a Democrat from Missouri, conducted a lengthy inquiry into the origins of the M-16 problem. Much of the credit for the hearings belongs to the committee’s counsel, Earl J. Morgan. The hearing record, nearly 600 pages long, is a forgotten document, which received modest press attention at the time and calls up only dim recollections now. Yet it is a pure portrayal of the banality of evil.
Nearly a century before American troops were ordered into Vietnam, weapons designers had made a discovery in the science of “wound ballistics.” The discovery was that a small, fast-traveling bullet often did a great deal more damage than a larger round when fired into human or (for the experiments) animal flesh. A large artillery round might pass straight through a human body, but a small bullet could act like a gouge. During the early stages of the congressional hearing, Ichord asked Eugene Stoner, the designer of the original version of the M-16, to explain the apparent paradox of a small bullet’s destructive power. The answer emerged in the following grisly exchange.
ichord: One army boy told me that he had shot a Vietcong near the eye with an M-14 [which uses a substantially heavier bullet] and the bullet did not make too large a hole on exit, but he shot a Vietcong under similar circumstances in the same place with an M-16 and his whole head was reduced to pulp. This would not appear to make sense. You have greater velocity but the bullet is lighter.
stoner: There is the advantage that a small or light bullet has over a heavy one when it comes to wound ballistics. … What it amounts to is the fact that bullets are stabilized to fly through the air, and not through water, or a body, which is approximately the same density as the water. And they are stable as long as they are in the air. When they hit something, they immediately go unstable. … If you are talking about .30-caliber [like a bullet used in the M-14], this might remain stable through a human body. … While a little bullet, being it has a low mass, it senses an instability situation faster and reacts much faster. … this is what makes a little bullet pay off so much in wound ballistics.
The farsighted Willard G. Wyman, the commanding general of the Continental Army Command, had asked Stoner to design a rifle precisely to take advantage of the “payoff” of smaller bullets. The AR-15, the precursor of the M-16, used .22-calliber bullets instead of the .30-caliber that had long been standard for the Army. As early as 1928, an Army “Caliber Board” had conducted firing experiments in Aberdeen, Maryland, and had then recommended a move toward smaller ammunition, perhaps of the .27-caliber range; but the Army, for reasons that were partly technical but largely traditional, refused then and for the next thirty-five years to change from the .30-caliber bullet, which it chose to describe as “full-sized.”
A second discovery about weaponry lay behind the design of Eugene Stoner’s AR-15. In studies of combat units during World War II, S. L. A. Marshall found that nearly four fifths of combat soldiers never fired their weapons during battle. This finding prompted the Army to take a closer look at the weapons the soldiers used. It turned out that one group of soldiers was an exception to this rule: those who carried the Browning automatic rifles (BARs). These were essentially portable machine guns, which could spray out bursts of continuous fire. (The rifles that the other soldiers carried, M-1s, were “semiautomatic,” requiring a separate trigger squeeze for each round.) Within a combat group, firing would begin with the BAR man and spread out from him. The nearer a soldier with an M-1 stood to the BAR man, the more likely he was to fire. The explanation most often suggested was that the infantryman carrying a normal rifle felt that his actions were ultimately futile. John Keegan said in The Face of Battle, “Infantrymen, however well-trained an well-armed, however resolute, however ready to kill, remain erratic agents of death. Unless centrally directed, they will choose, perhaps badly, their own targets, will open and cease fire individually, will be put off their aim by the enemy’s return of fire, will be distracted by the wounding of those near them, will yield to fear or excitement, will fire high, low, or wide.” The normal infantryman could not see the enemy clearly or have any sense of whether he had made a hit. The BAR man, by contrast, had the sense that he could dominate a certain area—“hose it down,” in the military slang—and destroy anyone who happens to be there.
[…]
At about the time the m-14 was adopted as the Army’s standard, Eugene Stoner was completing his work on the AR-15. Stoner was known as one of the great figures in the special calling of small-arms design. Like some of the other outstanding American rifle designers—including John Browning, inventor of the Browning automatic rifle, who had to sell his weapons to foreign governments after rejection by the American ordnance corps—Stoner had never seen his models win easy acceptance by the Army. He was working for the Armalite Corporation when he finished developing the AR-15.
The rifle combined several advantages. One was the lethal “payoff” that came with its .22-caliber bullets. The smaller, lighter ammunition meant that the rifle could be controlled on automatic fire by the average soldier, because its kick was so much less than the M-14’s. The rifle itself was also lighter than the M-14. These savings in weight meant that a soldier using the AR-15 could carry almost three times as many rounds as one with the M-14. This promised to eliminate one of the soldier’s fundamental problems in combat: running out of ammunition during a fire fight. The rifle had two other, technical advantages. One was the marvelous reliability of its moving parts, which could feed, fire, extract, and eject 600 or 700 cartridges a minute and practically never jam. The other was a manufacturing innovation that drastically cut the cost of the weapon. The parts were stamped out—not hand-machined, as in previous rifles—and they could be truly mass-produced. The stock was made of plastic, which further cut the cost, and to traditionalists, this was one more indication that the AR-15 was not a real weapon. They said that you couldn’t use a plastic rifle as a club. Stoner’s reply, in effect, was that with the AR-15’s reliability and destructive power you wouldn’t need to.
The AR-15 was tested in 1958 at three military bases. The reports were favorable, but there were reservations from the ordnance establishment about the propriety of using such small-caliber ammunition. To reconcile the differences in opinion, the Army commissioned an extensive series of tests at its Combat Developments Experimentation Command, known as CDEC, at Ford Ord, California. These tests ran from the fall of 1958 until the spring of 1959, and were designed not to follow the usual marksman’s pattern but to simulate the conditions of small squads in combat. In the tests, the AR-15 was matched against the M-14 and another lightweight rifle, made by Winchester. The results, released in May of 1959, included these findings:
a. With a total combat weight per man equivalent to that planned for riflemen armed with the M-14, a squad consisting of from 5-7 men armed with the [AR-15] would have better hit distribution and greater hit capability than the present eleven-man M-14 squad. …
b. By opinion poll, the experimentation troops favor the [AR-15] because of its demonstrated characteristics of lightness in weight, reliability, balance and grip, and freedom from recoil and climb on full automatic. …
h. The attributes demonstrated by the prototype weapons of the lightweight high-velocity category indicate an overall combat potential superior to that of the M-14. Such advantages include … lightness in weight of arms and ammunition, ease of handling, superior full automatic firing capability, accuracy of the Winchester and functional reliability of the Armalite [AR-15].
The report’s conclusion was that the Army should develop a lightweight rifle “with the reliability characteristics of the Armalite” to replace the M-14. “Concurrent with the adoption of a lightweight high-velocity rifle,” the report said, “serious consideration [should] be given to reduction in the size of the present squad,” in light of the increased firepower of the new weapons. The repeated references to the “reliability” of the AR-15 bear emphasis, in view of the weapon’s unreliability after it had been transformed into the M-16 and sent to war.
After the CDE tests, the Army admitted the theoretical “promise” of the lightweight system but rejected it as a practical proposition. Emphasizing the importance of having all rifles and machine guns use the same ammunition, the Army ordered full production of the .30-caliber M-14.
However, advocates of the AR-15 enlisted the support of a redoubtable gun enthusiast, General Curtis Lemay, then the Air Force’s Chief of Staff. Based on his interest, the Air Force conducted further tests and inspections and declared the AR-15 its “standard” model in January of 1962. The Air Force then took a step that later had enormous significance. On the advice of the Armalite Corporation, which owned the design for the rifle, and of Colt, which had the contract to manufacture it, the Air Force tested the ammunition that the Remington Arms Company had developed for the AR-15. After the tests, the Air Force declared the ammunition suitable for its purposes. In May of 1962, it ordered 8,500 rifles from Colt and 8.5 million rounds of ammunition from Remington…
Read the whole thing it’s fascinating.