The
5.56×45mm NATO (official
NATO nomenclature
5.56 NATO, commonly pronounced "five-five-six") is a
rimless bottlenecked
centerfire intermediate cartridgefamily developed in the late 1970s in Belgium by
FN Herstal.
[5] It consists of the SS109, L110, and SS111 cartridges.
The Army is changing its standard ammunition primarily to improve performance against body armor and increase effective range, moving from 5.56mm to 6.8mm rounds for its new
Next Generation Squad Weapon (NGSW). This shift aims to enhance lethality and accuracy at longer distances, a key consideration in modern warfare.