None to really speak of. They are, for the most part, one and the same. The 9mm NATO is merely a variant of the 9mm Luger loaded for military specifications.
NATO-north Atlantic treaty organisation
Their is no NATO M4. NATO countries that use the M4 either contract the purchase or license the production.
5.56x45 is the ammunition originally developed for the M16 rifle. Many people mistakenly claim it is the same as .223 Remington ammunition, although this is not true - while the dimensions are similar, neck angles and other measurements differ between the two cartridges. In the late 1970s, after the US had announced that troops stationed in Europe would be equipped with M16 rifles, NATO sought a cartridge to make standard amongst their forces, in order for there to be cross compatability between NATO military forces. The weight of the 5.56x45 projectile was increased from 55 to 62 grains.
Of course you can. The .223 is the civilian version of the 5.56x45mm NATO ammunition. They are slightly different but the difference is constantly neglected due to the fact that it is safe to shoot. Hope this helps.
it's comparable to a 7.62 NATO round, just a little bit longer.
430 MPa (62,366 psi) for NATO standard 5.56 ammunition. This is what is required of all NATO test barrels, which are measured at the mouth of the casing.
The 9x19mm NATO is a variant of the Parabellum round. It's firing pressure is simply a little bit higher (about 2,000 PSI higher).
Shank (.223 Remington) - 0.4370 / (NATO 5.56) - 0.4370 / (Difference) - 0.0000 Base Diameter (.223 Remington) - 0.3760 / (NATO 5.56) - 0.3780 / (Difference) - 0.0020 Shoulder Diameter (.223 Remington) - 0.3553 / (NATO 5.56) - 0.3560 / (Difference) - 0.0007 Neck-2 (.223 Remington) - 0.2550 / (NATO 5.56) - 0.2550 / (Difference) - 0.0000 Neck-2/Case Mouth (.223 Remington) - 0.2540 / (NATO 5.56) - 0.2550 / (Difference) - 0.0010 Freebore Diameter (.223 Remington) - 0.2245 / (NATO 5.56) - 0.2270 / (Difference) - 0.0025 Pilot Diameter (.223 Remington) - 0.2180 / (NATO 5.56) - 0.2180 / (Difference) - 0.0000 Base-to-Case Mouth (.223 Remington) - 1.7720 / (NATO 5.56) - 1.7750 / (Difference) - 0.0030 Base-to-Shoulder (.223 Remington) - 1.2340 / (NATO 5.56) - 1.2380 / (Difference) - 0.0040 Neck Length (.223 Remington) - 0.2200 / (NATO 5.56) - 0.2180 / (Difference) - -0.0020 Freebore Length (.223 Remington) - 0.0250 / (NATO 5.56) - 0.0500 / (Difference) - 0.0250 Rim/Belt Thickness (.223 Remington) - 0.2000 / (NATO 5.56) - 0.2000 / (Difference) - 0.0000 Shoulder Angle (Degrees) (.223 Remington) - 23.0 / (NATO 5.56) - 23.0 / (Difference) - 0.0 Throat Angle (Degrees) (.223 Remington) - 3.1 / (NATO 5.56) - 2.5 / (Difference) - -0.6
5.56x45mm NATO or .223 Remington. They are dimensionally similar rounds, but they are not the same. Some AR-15 rifles have smaller throats than others. If it is too small, you'll only be able to fire .223 Remington ammunition in the firearm, as the area of the throat will be too small to accommodate the higher pressures generated by firing 5.56 NATO ammunition. If the throat is reamed properly, you should be able to fire both types of ammunition in the weapon. There's no way to tell just by looking. If you try to fire 5.56 NATO ammunition in your AR and the primer pops out of the spent casing (in a best case scenario), get a 5.56 reamer (they're around $240). The reamer will widen the throat to accommodate the hotter 5.56 NATO ammunition.
POSSIBLY- and this is a stab in the dark- 7.62 NATO- similar to the civilian .308 Winchester. RG is a headstamo used by the Radway Green ammunition plant in Britain. In 1950, the standard rifle used the 7.62 NATO cartridge. Again, just a guess.
Standardization. They standardise on certain rounds (among other things). That way, in the event of the breakout of war between NATO and Warsaw Pact forces (which never occurred), if, say, a German unit was low on ammunition, and needed resupply, they could be resupplied with Belgian, American, British, etc. ammo.
It's primarily intended to use the NATO standard 62 grain 5.56x45 cartridge.