Forums / Gun Discussion / What is the history behind the development of the .223/5.56mm round?

5 years 34 weeks ago, 11:31 AM

samD

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Studies of the fighting in WWII determined that most of the infantry fighting took place at distances under 200 yards, and those figures have not changed much in modern conflicts.(1) This was a revelation at the time and a controversial one, as ever since the development of smokeless powder, the long distance capabilities of military rifles had been stressed. It was common for rifles designed in the 1890s through the 1940s to have sights adjustable out to 1,000 or even 2,000 yards, and often not having an adjustment below 200 or 300 yards. Obviously, there was a discrepancy between the design of these rifles and how they were most often used.

Following WWII, the US military decided it needed a select-fire, detachable-magazine rifle. (The WWII-era M1 Garand had originally been designed with a detachable magazine, but at the time, the military decided they were a liability for a standard, front-line infantry rifle and had the M1 redesigned.) During this period during the late 40s and early 50s, many nations were experimenting with smaller-caliber rifles that were controllable in full-auto and allowed more rounds to be carried. The US military insisted on a 30 caliber rifle, though, and merely shortened the existing .30-06 Springfield (7.62x63mm) round to create the 7.62×51mm round, which Winchester released commercially as the .308 Winchester. The US also forced this round onto the newly-formed NATO, over protests that it was too much cartridge, would require rifles to be too heavy, and wouldn't be controllable on full auto. The first point is arguable, but the last two were certainly true. Still, the US military, having determined that the Belgium-designed FN FAL was a better rifle then the domestic M14 (a modified M1 Garand), chose the M14 anyway. Such is politics.

The M14 program was a political minefield and during the early 1960s, minor US involvement as "advisors" in the southeast Asian country called Vietnam was beginning to escalate. It didn't take long before the Vietnam expansion, coupled with manufacturing problems with some M14 contractors, resulted in too many soldiers and too few M14s. The military initially pulled WWII M1 Garands out of storage and pressed them back into service, but these long, heavy rifles were poorly suited to the jungle environment of Vietnam. During this time, Eugene Stoner of ArmaLite, the armament division of Fairchild Aircraft, had designed a rifle called the ArmaLite Model 10, or AR-10, which was chambered in the current NATO round of 7.62×51mm. Though the AR-10 was produced too late to enter the M14 competition, ArmaLite hoped to sell the AR-10 to foreign militaries.

Meanwhile, there was a faction of the US Military and the Congress which supported the idea of a lightweight, select-fire rifle firing a mid-power, small-caliber, high-velocity (SCHV) cartridge. After seeing the ArmaLite AR-10, they discussed their desire for a scaled-down model. ArmaLite engineers Jim Sullivan and Bob Fremont scaled down the AR-10 to fit the hot varmint cartridge of the day, the .222 Remington. During some preliminary military testing, it was decided that the .222 Rem wasn't quite powerful enough. Though the .222 Remington Magnum existed and had the power they were looking for, the severe shoulder angle would have prevented positive feeding in a semi-auto, and so it was decided that the best solution was to lengthen the .222 Rem case. The result was the 5.56×45mm cartridge, designed by G. A. Gustafson, which Remington released commercially as the .223 Remington. This cartridge has virtually identical ballistics as the .222 Mag and, over time, the wide availability of .223 guns and ammo has lead to the demise of the .222 and .222 Mag cartridges.

The AR15 was initially adopted by the Air Force, but the need for rifles for soldiers heading to Vietnam gave the "medium-power cartridge" supporters an opening and the AR15 rifle was hastily procured, initially as a one-time purchase. Continued problems with the M14 program lead to the official adoption of the AR15, which was given the US military designation "M16."

5 years 34 weeks ago, 10:42 PM

runawaygun762

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samD

Whew, glad you posted this. I was beginning to wonder.

"I have always been a soldier. I have known no other life. The calling of arms, I have followed from boyhood. I have never sought another." From The Virtues of War, by Steven Pressfield.
5 years 34 weeks ago, 8:41 AM

samD

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LOL. We know you are a munitions wizard, but some of the others of us are here to learn. And learn we must to be ready for the Islamic Facist and liberal weenies...

5 years 34 weeks ago, 7:09 AM

runawaygun762

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samD, liberal weenies?

I'm staying away from weenies, whether they are on libs or conservatives. You're making me wonder. Hah hah hah. I smell funny. Speaking of smelling funny, did you know dead Iraqis actually smell better than live ones? It's weird. Of course, some of the Iraqis I've smelled were after suicide attacks and they smelled a bit like BBQ and gasoline. Mmm, finger lickin' good.

"I have always been a soldier. I have known no other life. The calling of arms, I have followed from boyhood. I have never sought another." From The Virtues of War, by Steven Pressfield.
5 years 32 weeks ago, 10:52 PM

paco2505

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History

The previous standard NATO rifle cartridge was the 7.62x51mm NATO, derived from the .308 Winchester rifle cartridge and designed to replace the U.S. military's .30-06 Springfield rifle cartridge. At the time of selection, there had been criticism that the 7.62 mm was too powerful for modern service rifles, causing excessive recoil, and that the weight of the ammunition did not allow for enough fire power in modern combat. A soldier can carry nearly twice as much 5.56 mm ammunition as 7.62 mm for the same weight.

During the late 1950s, ArmaLite and other U.S. firearm designers started their individual Small Caliber/High Velocity (SCHV) assault rifle experiments using the commercial .222 Remington cartridge. When it became clear that there was not enough powder capacity to meet U.S. Continental Army Command's (CONARC) velocity and penetration requirements, ArmaLite contacted Remington to create a similar cartridge with a longer case body and shorter neck. This became the .222 Remington Special. At the same time, Springfield Armory's Earle Harvey had Remington create an even longer cartridge case then known as the .224 Springfield. Springfield was forced to drop out of the CONARC competition, and thus the .224 Springfield was later released as a commercial sporting cartridge known as the .222 Remington Magnum. To prevent confusion with all of the competing .222 cartridge designations, the .222 Remington Special was renamed the .223 Remington. After playing with their own proprietary cartridge case design, the .224E1 Winchester, Winchester eventually standardized their case dimensions, but not overall loaded length, with the .222 Remington Special to create a cartridge known as the .224E2 Winchester. With the U.S. military adoption of the ArmaLite AR-15 as the M16 rifle in 1963, the .223 Remington was standardized as the 5.56x45mm. However, the .223 Remington was not introduced as a commercial sporting cartridge until 1964.

The British had extensive evidence with their own experiments into an intermediate cartridge since 1945 and were on the point of introducing a .280 inch (7 mm) cartridge when the selection of the 7.62 mm NATO was made. The FN company had also been involved. The concerns about recoil and effectiveness were effectively overruled by the US within NATO, and the other NATO nations accepted that standardization was more important at the time than selection of the ideal cartridge. However the concerns would prove to be valid and led to the development of the 5.56 cartridge.

During the 1970s, NATO members signed an agreement to select a second, smaller caliber cartridge to replace the 7.62 mm NATO. Of the cartridges tendered, the 5.56 mm was successful, but not the 5.56 mm loading (M193 Ball) as used by the U.S. at that time. Instead, the Belgian FN SS109 loading was chosen for standardization. The SS109 used a heavier bullet with a steel core inserted, fired at a lower muzzle velocity for better long-range performance, specifically to meet a requirement that the bullet be able to penetrate through one side of a steel helmet at 600 m. Some believe that this requirement has made the M855 less capable of fragmentation than the M193 as discussed below.

Americans would define the shoulder angle at alpha/2 = 23 degrees. The common rifling twist rate for this cartridge is 178 mm (1 in 7 in) or 229 mm (1 in 9 in), 6 grooves, Ø lands = 5.56 mm, Ø grooves = 5.59 mm, land width = 1.88 mm and the primer type is small rifle.

According to the official NATO proofing guidelines the 5.56x45mm NATO case can handle up to 430 MPa (62,367 psi) piezo service pressure. In NATO regulated organizations every rifle cartridge combo has to be proofed at 125% of this maximum pressure to certify for service issue. This is equal to the C.I.P. maximum pressure guideline for the .223 Remington cartridge, that is the 5.56x45mm NATO parent cartridge.

"Show me a man who will jump out of an airplane, and I'll show you a man who'll fight." --General James M. Gavin
5 years 32 weeks ago, 10:57 PM

fordvg

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Welcome paco2505

Welcome to the site paco. Great to have you here with us.

"WAR IS A RACKET, I spent most of my time being a high-class muscle-man for Big Business, for Wall Street, and for the Bankers." Major-General Smedley Darlington Butler USMC Ret. 2 time Medal of Honor winner.
5 years 32 weeks ago, 1:29 AM

Pkato

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P unk
A ss
C ommie
O bama supporter,

Don't believe anything he writes!!!

haha...just kidding Amigo! Ebear, you got another recruit.

PKato

Patrolman Kato
Firearms stand next in importance to the Constitution itself.
They are the American people's liberty teeth and keystone
under independence. -- George Washington

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