I presume you're referring to the 7.62x51 NATO cartridge, the civilian version of which is 308 Winchester. Both use a .308 caliber bullet of various weights.
Another standard NATO cartridge is 5.56 NATO. The civilian version of that cartridge is 223 Remington.
Both military cartridges have characteristics (bullet weight, powder charges, etc.) that may preclude complete interchangeability with some civilian/hunting firearms.
A quick note, in regards to the .308 Winchester being referred to as a civilian version of the 7.62x51 and the .223 Remington being a civilian version of the 5.56x45.. this is not true. The cartridges are dimensionally similar, but are not one in the same, varying in case thickness, neck angles, and other features.
7.62 mm (or 30 caliber) and 5.56 mm (or 223 caliber) are common rifle cartridges. Pistols, machine guns, and artillery will of course be different from these.
5.56x45mm NATO
7.62 NATO
5.56x45 NATO
you can not use metal bbs in airsoft guns at all. they are not compatible because they are both built differently.
No such thing. You can have small caliber but not low caliber.
It uses a 9x19mm Parrabullum NATO round, which is the standard round for most pistols and submachine guns made by countries in NATO.
7.62x51 NATO
With VERY FEW exceptions all BB guns use the same size BB .177 Caliber.
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.
7.65mm is .32 caliber. I own one of these guns and love it.
4.5 cal (9mm) like most guns