The mainstream media will often refer to military-style assault rifles as high-power rifles, when they are, arguably, just the opposite. The main battle rifles of WWI and WWII were high-power rifles, but the M16 shoots a teeny-tiny round. So, why do American soldiers shoot a glorified .22?
In 1948, the Army organized the civilian Operations Research Office (ORO), mirroring similar operations research organizations in the United Kingdom. One of their first efforts, Project ALCLAD, studied body armor and the conclusion was that they would need to know more about battlefield injuries in order to make reasonable suggestions. Over 3 million battlefield reports from WWI and WWII were analyzed and over the next few years they released a series of reports on their findings.
The conclusion was that most combat takes place at short range. In a highly mobile war, combat teams ran into each other largely by surprise; and the team with the higher firepower tended to win. They also found that the chance of being hit in combat was essentially random — that is, accurate “aiming” made little difference because the targets no longer sat still. The number one predictor of casualties was the total number of bullets fired. Other studies of behavior in battle revealed that many U.S. infantrymen (as many as 2/3) never actually fired their rifles in combat. By contrast, soldiers armed with rapid fire weapons (such as submachine guns) were much more likely to have fired their weapons in battle. These conclusions suggested that infantry should be equipped with a fully-automatic rifle of some sort in order to increase the actual firepower of regular soldiers. It was also clear, however, that such weapons dramatically increased ammunition use and in order for a rifleman to be able to carry enough ammunition for a firefight they would have to carry something much lighter.
Existing rifles were poorly suited to real-world combat for both of these reasons. Although it appeared the new 7.62 mm T44 (precursor to the M14) would increase the rate of fire, its heavy 7.62 mm NATO cartridge made carrying significant quantities of ammunition difficult. Moreover, the length and weight of the weapon made it unsuitable for short range combat situations often found in jungle and urban combat or mechanized warfare, where a smaller and lighter weapon could be brought to bear faster.
These efforts were noticed by Colonel René Studler, U.S. Army Ordnance’s Chief of Small Arms Research and Development. Col. Studler asked the Aberdeen Proving Ground to submit a report on the smaller caliber weapons. A team led by Donald Hall, director of program development at Aberdeen, reported that a .22 inch (5.56 mm) round would have performance equal to larger rounds in most combat. With the higher rate of fire possible due to lower recoil it was likely such a weapon would inflict more casualties on the enemy. His team members, notably William C. Davis, Jr. and Gerald A. Gustafson, started development of a series of experimental .22 (5.56 mm) cartridges.