223 Remington / 5.56mm NATO Ammo | SGAmmo.com
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WEBThe .223 Rem / 5.56 NATO round is by far the most common rifle cartridge used by civilians in the USA. 223 Rem and 5.56 NATO are the most common chamberings used in the Americas most popular rifle, the AR15. The .223 Remington and 5.56×45mm NATO cartridges and chamberings are similar but not identical.
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