The 5.56×45mm NATO (official NATO nomenclature 5.56 NATO, but often pronounced "five-five-six") is a rimless bottlenecked intermediate cartridge family developed in the late 1970s in Belgium by FN Herstal. It consists of the SS109, L110, and SS111 cartridges. On 28 October 1980, under STANAG 4172, it was standardized as the second standard service rifle cartridge for NATO forces as well as many non-NATO countries. Though they are not entirely identical, the 5.56×45mm NATO cartridge family was derived from and is dimensionally similar to the .223 Remington cartridge designed by Remington Arms in the early 1960s. History In 1954, the larger 7.62×51mm NATO rifle cartridge was selected as the first standard NATO rifle cartridge. At the time of selection there had been criticism that the recoil power of the 7.62×51mm NATO, when fired from a handheld lightweight modern service rifle, did not allow a sufficient automatic rate of fire for modern combat. The British had extensive evidence through their own experimentation with intermediate cartridges since 1945, and were on the point of adopting the .280 (7 mm) cartridge when the selection of 7.62×51mm (.300) as the NATO standard was made. The FN company had also been involved in the development of the .280 round, including developing a version of the FN FAL in .280. Concerns about the recoil and overall effectiveness of 7.62 mm were overruled by the US, and the other NATO nations accepted that standardization was more important than the selection of a cartridge that was otherwise ideal. The development of the cartridge that eventually became the .223 Remington (from which 5.56mm NATO would eventually be developed) would be intrinsically linked to the development of a new lightweight combat rifle. The cartridge and rifle were developed as one unit by Fairchild Industries, Remington Arms, and several engineers working toward a goal developed by U.S. Continental Army Command (CONARC). Early development work began in 1957. A project to create a small-calibre, high-velocity (SCHV) firearm was created. Eugene Stoner of Armalite was invited to scale down the AR-10 (7.62mm) design. Winchester was also invited to participate. The parameters that were requested by CONARC: Springfield Armory's Earle Harvey lengthened the .222 Remington cartridge case to meet the requirements. It was then known as the .224 Springfield. Concurrently with the SCHV project, Springfield Armory was developing a 7.62mm rifle. Harvey was ordered to cease all work on the SCHV to avoid any competition