| 5.56x45mm NATO, .30-30 Win., 7.62X51 NATO.|
|Manufacturer:||Lake City Armory, Remington|
The 5.56x45mm NATO caliber is a rifle catridge originally designed for the M-16 rifle of the U.S. military. It fires a small, high-velocity bullet for very good range and accuracy. It has been heavily criticized for it's low stopping power compared to the 7.62x51mm NATO round or even the Soviet 7.62x39 mm.
Firing a 55 grain projectile at 3,200 fps it produces approximately 1,250 ft-lbs of energy. Compared to the NATO and Soviet 7.62mm(2,500 and 1,550 ft-lbs respectively) it is underpowered. However, it is half the weight allowing the soldier to carry twice the ammunition. Having been in the U.S. arsenal for about 40 years it has proven itself as a capable and lethal weapon caliber, so much so that is became the standardized rifle caliber of the U.N. military forces. The current issue M855 ammunition uses the SS109 62 grain steel-core bullet with a full metal jacket.
The cartridge has also been adapted for the civilian market, called the .223 Remington, becoming popular with small-game hunters and target shooters. Specialized rounds have also been developed for designated marksmen rifles(DMR's), firing heavier 77gr. projectiles for extended range and accuracy.