5.56×45mm NATO
intermediate firearms cartridge
The 5.56×45mm NATO (official NATO nomenclature 5.56 NATO, commonly pronounced "five-five-six") is a rimless bottlenecked centerfire 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 identical, the 5.56×45mm NATO cartridge family was derived from the .223 Remington cartridge designed by Remington Arms in the early 1960s, which has a near-identical case. However, firing chamber dimensions differ slightly between rifles manufactured for the designated cartridges. The differences may cause unsafe chamber pressures when firing 5.56 NATO in rifles designed for .223 Remington. Therefore, this combination is not recommended.
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 in full automatic mode, did not allow for sufficient control, so the automatic follow-on shots would not hit the intended target but scatter around it.
The British had extensive evidence from their own experimentation with intermediate cartridges since 1945, and were on the point of adopting the .280 (7 mm × 43mm) cartridge when the selection of 7.62×51mm (.308) as the NATO standard was made.
Begin with the source’s own compact description: “5.56×45mm NATO” is intermediate firearms cartridge. The dossier treats that line as a proposition to test through 45mm, NATO and intermediate, not as a finished interpretation.
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This entry incorporates text from “5.56×45mm NATO” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.