5.56x45mm NATO

5.56x45mm



In the 1950s, the 7.62×51mm NATO rifle cartridge (sold commercially as the .308 Winchester rifle cartridge) was selected to replace the .30-06 Springfield as the standard NATO rifle cartridge. At the time of selection, there had been criticism that the 7.62×51mm NATO was too powerful for light weight modern service rifles, causing excessive recoil, and that the ammunition did not allow for sufficient 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 7.62×51mm 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 7.62×51mm NATO round became NATO standard the US was already engaged in research of their own, which ultimately led to the 5.56×45mm NATO 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. With the U.S. military adoption of the ArmaLite M16 rifle in 1963, the .223 Remington was standardized as the 5.56×45mm NATO. As a commercial sporting cartridge the .223 Remington was only introduced in 1964.

The 5.56×45mm cartridge, along the M16 rifle, were initially adopted by U.S. infantry forces as interim solutions to address the weight and control issues experienced with the 7.62×51mm round and M14 rifle. In the late 1950s, the Special Purpose Individual Weapon program sought to create flechette rounds to allow troops to fire sabot-type projectiles to give a short flight time and flat trajectory with a muzzle velocity of 1,200 metres per second (3,900 ft/s) to 1,500 metres per second (4,900 ft/s). At those speeds, factors like range, wind drift, and target movement would no longer affect performance. Several manufacturers produced varying weapons designs, including traditional wooden, bullpup, "space age," and even multi-barrel designs with drum magazines. All used similar ammunition firing a 1.8 mm diameter dart with a plastic "puller" sabot filling the case mouth. While the flechette ammo had excellent armor penetration, there were doubts about their terminal effectiveness against unprotected targets. Conventional cased ammunition was more accurate and the sabots were expensive to produce. The SPIW never created a weapons system that was combat effective, so the M16 was retained, and the 5.56 mm round was kept as the standard U.S. infantry rifle cartridge.

In a series of mock-combat situations testing in the early 1960s with the M16, M14 and AK-47, the Army found that the M16'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 M16 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 NATO ammunition as 7.62×51mm NATO for the same weight, which would allow them a better advantage against a typical NVA unit armed with AK-47s.

Prices for a Box of 5.56 - 1501 RU