5.56×45mm NATO - History

History

The previous standard NATO rifle cartridge was the 7.62×51mm NATO, derived from the .308 Winchester rifle cartridge and designed to replace the .30-06 Springfield rifle cartridge in the U.S. military. At the time of selection, there had been criticism that the 7.62 mm was too powerful for modern service rifles, causing excessive recoil, and that the weight of the ammunition did not allow for enough rate of fire in modern combat.

The British had extensive evidence with their own experiments into an intermediate cartridge since 1945 and were on the point of introducing a .280 inch (7 mm) cartridge when the selection of the 7.62 mm NATO was made. The FN company had also been involved. The concerns about recoil and effectiveness were effectively overruled by the US within NATO, and the other NATO nations accepted that standardization was more important at the time than selection of the ideal cartridge. However, whilst the 7.62 round became NATO standard the US was already engaged in research of their own, which ultimately lead to the 5.56 cartridge.

During the late 1950s, ArmaLite and other U.S. firearm designers started their individual Small Caliber/High Velocity (SCHV) assault rifle experiments using the commercial .222 Remington cartridge. When it became clear that there was not enough powder capacity to meet U.S. Continental Army Command's (CONARC) velocity and penetration requirements, ArmaLite contacted Remington to create a similar cartridge with a longer case body and shorter neck. This became the .222 Remington Special. At the same time, Springfield Armory's Earle Harvey had Remington create an even longer cartridge case then known as the .224 Springfield. Springfield was forced to drop out of the CONARC competition, and thus the .224 Springfield was later released as a commercial sporting cartridge known as the .222 Remington Magnum. To prevent confusion with all of the competing .222 cartridge designations, the .222 Remington Special was renamed the .223 Remington. After playing with their own proprietary cartridge case design, the .224E1 Winchester, Winchester eventually standardized their case dimensions, but not overall loaded length, with the .222 Remington Special to create a cartridge known as the .224E2 Winchester. With the U.S. military adoption of the ArmaLite AR-15 as the M16 rifle in 1963, the .223 Remington was standardized as the 5.56×45mm. As a commercial sporting cartridge the .223 Remington was only introduced in 1964.

In a series of mock-combat situations testing in the early 1960s with the AR-15, M14 and AK-47, the Army found that the AR-15's small size and light weight allowed it to be brought to bear much more quickly. Their final conclusion was that an 8-man team equipped with the AR-15 would have the same fire-power as a current 11-man team armed with the M14. U.S. troops were able to carry more than twice as much 5.56×45mm ammunition as 7.62×51mm for the same weight, which would allow them a better advantage against a typical NVA unit armed with AK-47s.

(*AK-47 magazines are much heavier than M14 and M16 magazines)

In 1977, NATO members signed an agreement to select a second, smaller caliber cartridge to replace the 7.62 mm NATO cartridge. Of the cartridges tendered, the 5.56×45mm was successful, but not the 55 gr M193 round used by the U.S. at that time. The wounds produced by the M193 round were so devastating that many consider it to be inhumane. Instead, the Belgian 62 gr SS109 round was chosen for standardization. The SS109 used a heavier bullet with a steel core and had a lower muzzle velocity for better long-range performance, specifically to meet a requirement that the bullet be able to penetrate through one side of a steel helmet at 600 meters. This requirement made the SS109 (M855) round less capable of fragmentation than the M193 and was considered more humane

The Soviet Union followed suit in 1974 by adopting the 5.45×39mm (also small caliber/high velocity). The People's Republic of China did likewise with the 5.8×42mm DBP87 round that was ready for production in 1987.