5.56 x 45 mm NATO
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5.56 x 45 mm NATO is the size of the standard rifle ammunition for NATO forces. It is similar to and thus commonly, if incorrectly, called the Remington .223 cartridge.
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History
The previous standard NATO round was the 7.62 mm (based on the .30 rifle cartridge). At the time of selection, there had been criticism that the [[7.62 mm caliber was overpowered for modern warfare, and the use of semi-automatic fire, and smaller alternatives had been tendered. In light of experiences with the M14 rifle and the 7.62 mm cartridge, 5.56 mm amunition was introduced for use in the American M16 rifle in the 1960s. There was then an agreement to change to a smaller caliber and consequently a smaller cartridge too. Of the cartridges tendered the 5.56 mm was successful, but not the 5.56 laoding as used by the US at that time, but the Belgian offer, the SS109 loading, with a heavier bullet at a lower muzzle velocity for better long-range performance.
The cartridge is 57 mm (approximately 2.25 inches) long and 9.7 mm (0.38 inches) in diameter. The bullet itself is 0.75 inches (20 mm) long and 0.25 inches (6.375 mm) in diameter.
The Remington .223 cartridge has the same dimensions as the 5.56 x 45, but has a lower propelling charge, the NATO loading being the more powerful. While possible, it is not recommended to fire 5.56 NATO cartridges from firearms designed for the .223 Remington, but it is safe, if not effecttive, to fire a .223 Remington round from firearms designed for the 5.56.
Performance
The 5.56 NATO cartridge with the standard military ball bullet will penetrate approximately 15 to 20 inches (380 to 500 mm) into soft tissue. The cartridge propels the bullet fast enough so that at close range it yaws early on in penetrating tissue. The bullet will then fracture and fragment at the cannelure. This is due in part to the rotational energy imparted by the high rate of twist in newer M16 barrels (A2 and later models), and is responsible for the large wound profile generated by this cartridge at close ranges. This phenomenon of hydrostatic shock is at least fairly controversial, but seems to impart much greater damage to tissue than the wound track alone would suggest.
Comparison of 5.56 vs 7.62 NATO
5.56 NATO
- Size: 5.56 x 45 mm
- Bullet weight: 3.95 g
- Velocity: 930 m/s
- Energy: 1,700 J
7.62 NATO
- Size: 7.62x51
- Bullet weight: 9.33 g
- Velocity: 838 m/s
- Energy: 3,275
The NATO Ball round (U.S. = M855) can also penetrate up to 3 mm of steel while the Armor-piercing variant (U.S. = M995) can penetrate up to 6 mm.
Use
Many nations and weapons use the 5.56 mm NATO cartridge.
Weapons using 5.56 mm ammunition include:
- American M16A1/A2/A3/A4, M4/M4A1 Carbine, CAR-15, XM177E1/E2, M733, AR-15, and other rifles of the Armalite family
- American/Belgian M249 SAW / FN Minimi light machine gun
- Austrian Steyr AUG rifle
- Belgian FN FNC and FN F2000 rifles
- British L85 (SA80) rifle
- Canadian Diemaco C7/C8 rifles
- French FAMAS F1/G2 rifle
- German Heckler und Koch HK33, Heckler und Koch G36, HK23, and HK53 rifles and machine guns
- Israeli IMI Negev SAW, Galil assault rifle and Tavor TAR-21 bullpup assault rifle
- Italian Beretta AR 70/90 rifles
- Russian AK-101 and -105 rifles
- Singaporean SAR-21
- South African Vektor R4 and R5
- South Korean K2 rifle
- Remington Model 7615 Police rifle
Sources & External links
- FAS: 5.56 mm Ammunition (http://www.fas.org/man/dod-101/sys/land/556.htm)
- The Gun Zone: 5.56 mm FAQ (http://www.thegunzone.com/556faq.html)
- The Gun Zone: A 5.56mm Timeline (http://www.thegunzone.com/556dw.html)
- I.M.I Small Arms Ammunition Division (http://www.imisammo.co.il/10162b.htm)