5,56 mm NATO

The 5,56 mm NATO or 5,56x45 mm ( 5.56 X 45 mm NATO in English), standardized in STANAG 4172, is a type of cartridge for Fusil S. It thus acts of a Caliber standard among the armed forces of NATO those of other countries non-member. The 5,56 mm is derived from the .223 Remington, but is not completely interchangeable with this last, in particular because of the higher pressure of the military cartouche 5,56 Misters.

History

5,56mm NATO was used the first time in the M16 then in the German HK 33, the Famas French and rifle Austrian Steyr AUG during the Années 1970. In 1980, NATO substituted it for the 7,62 mm NATO like standard ammunition for its rifles of attack. This new version was designed by the branch cartridge factory of FN Herstal. The 5,56x45 mm is drawn by some Mitrailleuse S and rifles machine gunners.

Development

In the medium of the Years 1950, three cartridges of gauge .224 were selected to succeed 7,62 mm NATO as principal a military cartouche of the American armed forces : .222 Winchester, .224 Springfield and .222 Special. The latter was developed by Eugene Stoner, of ArmaLite. All were versions improved of the cartridge .222 Remington. The .222 Special one was selected among the others and soon became known under the name of .223 Remington.

The .223 Remington appeared for the first time in 1957 as a military experimental cartridge in the rifle of attack ArmaLite AR-15. In 1964, it was officially adopted by the American army under designation 5,6 mm M193 Ball. It is used in the rifle with selective shooting M16 which is based on the original design of the AR-15. This cartridge was the work of Robert Hutton, who was editor technician for the magazine Guns & Ammo and which had a field of fire to the rifle in California. One of the requirements for the cartridge was that the projectile had, with 450 meters, an high speed with that of the sound (approximately 340 m/s are 1225 km/h with the sea level), something which one could not obtain with the .222 Remington. Working with Eugene Stoner, Bob Hutton drew a cartridge slightly longer than the .222 and required of Sierra to create a projectile of 55 grains boattail , i.e. with the shaped silhouette like the back of a boat. This form presents a better penetration in the air and loses its initial speed thus less quickly. This combination made it possible to satisfy the requirements.

At the end of the years 1970 FN Herstal proposed, for the light machine-gun FN Minimi, a version improved of the 5,56 named NATO SS109 (adopted under the name of M855 in the American army), which is today the standard of NATO and whose body contains steel in order to improve some of its ballistic characteristics like its perforating capacity. It makes however necessary a step of stripes of gun different (1 turn every 7 inches) from that used for the .223 Remington (1 turn every 12 inches). Certain manufacturers took the party to stripe the guns at a rate of 1 turn for 9 inches in order to offer a decent precision with the two versions of the ammunition.

Effectiveness of the 5,56 NATO

Although of a gauge and a power lower than other ammunition of rifle, the 5,56 NATO has a capacity of considerable destruction. Three reasons are advanced to explain this effectiveness:

Because of its form long and balanced on the back, it often rocks on its axis by penetrating a target. It crosses it while whirling causing thus more damage than an handgun would do it. This phenomenon is found on many military ammunition, in particular the 5,45x39 mm M74 whose effectiveness is disputed.
Its high-speed causes a sufficiently fast shock wave to exceed the capacities of elasticity of fabrics and to cause a final cavity whose diameter is largely higher than its gauge, the attenuating phenomenon when the stray bullet speed. This explanation remains disputed because the speed of sound in water (composing the human body with 70%) is of 1480 m/s, the ball is thus largely subsonic in fabrics.
At a distance lower than 100 meters, the constraints which the ball sudden with the impact are sufficiently important to cause its bursting, which causes considerable damage. A similar phenomenon occurs when it runs up against a bone which bursts then in small fragments. The balls splitting up or becoming deformed with the impact are prohibited since the first International Conference of the peace of $the Hague in 1899. This conclusion is defended by Martin Fackler, former military surgeon of the American army and gave place for the American troops using the Colt M4 to a more fragile ball in order to preserve the capacity of fragmentation in spite the lower initial speed induced by the limited length of the gun.

Military data sheet 5,56 mm US M855 (ordinary ball, green point) or Canada C77 (ordinary ball, gray point)

real Diameter of the projectile: 5,56 mm
Length case: 44,70 mm
Length Cartridge: 57,40 mm
Mass projectile: 4 grams
Mass cartridge: 11,20 grams
initial Speed: 950 m/s.
current Alternatives: M856 To trace (tracing, orange point), corresponding to L110 of the FN Herstal

Perfomances ballistics

Penetration

A ball of 5,56 NATO (US designation: M855) can transpierce 3 mm of steel, the perforating alternative (US Designation: M995) can on the other hand transpierce 6 mm of steel.

Effective range

Comparison between 5,56 NATO and 7,62 NATO

See too

the ammunition 5,45x39 mm M74, Soviet counterpart to 5,56 mm NATO.
the Swiss ammunition 5,6 mm, the Swiss equivalent of 5,56 mm NATO.

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