It's more a matter of where it's manufactured and by whom than the caliber. Several non-NATO nations also manufacture NATO standard ammo. For example, Russia manufactures the 5.56x45 and 7.62x51 to go along with export versions of NATO caliber firearms they manufacture, such as the AK-101. Their steel cased rounds are much less expensive than, say, American made M855 ammo.
5.56x45mm NATO
7.62 NATO
5.56x45 NATO
7.62x51 NATO
This is the approximate size of a .45 caliber round, the conversion being .443 inches.
Known as 7.62 NATO, it is similar to, but not EXACTLY the same as the .308 Winchester.
5.56mm x 45mm (5.56 is the diameter of the buller, 45mm is the length of the brass casing). NATO implies that this is THE 5.56mm round used by NATO forces. Similar to 7.62mm x 51mm NATO is the standard .30 caliber round use by NATO forces.
"The .223 Remington is a sporting cartridge with almost the same external dimensions as the 5.56x45mm NATO military cartridge."In short, 223 IS the caliber- .223 inches
The M60 machinegun fires the 7.62 NATO cartridge- very similar to the .308 Winchester.
It fires a 7.62x51mm NATO bullet, which is similar to a .308 Winchester.
it fires a 5.56 by 51 milimeter standard NATO round. no... the m-16 and m4 are 5.56 x 45 NATO. 5.56 x 51 doesnt exist. its a 7.62 x 51 NATO round that an m-14 fires.
At that time m16's had just come out and almost everyone had that.(caliber: .223 or 5.56 NATO)