Page 128 - Australian Defence Magazine Sep-Oct 2022

128 LAND WARFARE SMALL ARMS
SEPTEMBER-OCTOBER 2022 | WWW.AUSTRALIANDEFENCE.COM.AU
AUSTRALIAN HERITAGE
Since federation, Australia has fielded three military rifle cartridges and matching infantry rifles.
Through two world wars up to the late 1950s, Australian soldiers carried the .303 SMLE. As the US, UK, NATO and many others moved to the 7.62 NATO cartridge, so Australia followed, adopting the Belgian FN FAL as the L1A1 SLR.
In 1963, the US adopted the 5.56 cartridge and what be- came known as the M16 rifle, both better suited to the escalating war in the jungles of Vietnam. Some Australian soldiers in Vietnam carried M16s, though the SLR re- mained the primary infantry weapon.
In 1977, NATO nations agreed to follow the US and adopt the 5.56 round. Australia again followed, choosing the Austrian Steyr AUG rifle and FN Minimi LMG in 5.56.
6.8x51, 5.56x45, Cartridge designations such as 5.56 NATO indicate a standardised projectile weight and velocity.
The US uses some metrics but designates projectile weight in grains, an archaic measure based on a grain of wheat.
For ammunition, grains are regarded as a more intuitive unit of weight measurement than the metric equivalent. For example, the 135 grain projectile for the new 6.8x51 cartridges is 8.7478 grams.
MORE EFFECTIVE ARMS
The US quest for a new cartridge and weapons emerged from experiences in Iraq and particularly Afghanistan where insurgents frequently initiated contacts at 500 me- tres or more, beyond the most effective range of the 5.56 cartridge, regarded as most effective to around 300 metres.
Further, hardy insurgents could often remain in the fight after taking hits from 5.56 rounds.
Various studies highlighted the issues.
“In general, the requirements for the infantry squad are that they have weapons capable of reliable incapacitation from close range to a distance of 500 metres,” US Army Major Thomas Ehrhart said in his influential 2009 study of small arms lethality in Afghanistan.
“This capability does not exist in the current family of 5.56mm ammunition, either with military or with commer- cial off the shelf ammunition.”
Ehrhart cited two examples from his own experience.
A US soldier, accidentally shot in the shoulder in a live fire exercise was walking around smoking a cigarette 20 minutes later. In Iraq in 2003, an accidental discharge of a M249 LMG hit four soldiers, none sustaining life threat- ening wounds.
Australian soldiers in Afghanistan experienced just the same issues in fighting insurgents at long range.
One solution adopted by Australia and others was in- clusion of a designated marksman in each infantry squad. That’s a soldier equipped with a rifle in 7.62 able to engage longer range targets. For the Australian Army, the designat- ed marksman rifle is the German Heckler and Koch HK417.
With Iraq and Afghanistan behind and no current wars, the US Army in 2017 launched the Next Generation Squad Weapon (NGSW) program, considering replacements for the 5.56 and 7.62 cartridges, M4 rifle, M249 LMG (the US version of the Minimi) and M240 LMG (the US version of the FN MAG58).
Since the First World War, military ballisticians have ap- preciated that projectiles in calibres 6.5-7mm sat in a sweet spot, with the best combination of projectile mass and bal- listic performance.
NEW US PROJECTILES
The 2017 US Small Arms Ammunition Configuration Study concluded that defeat of body armour could only be achieved with heavier projectiles at higher velocities.
From that, the US military decided the new cartridge would be in 6.8mm calibre with a 135-grain full metal jacket (FMJ) projectile as standard.
It adopted the unusual course of providing 6.8 projec- tiles and leaving it to companies competing in the NGSW
“AS TECHNOLOGY CONTINUES TO IMPROVE, MATERIALS RELATED TO SOLDIER PROTECTION AND OPTIONS THAT ARE CAPABLE OF DELIVERING MORE ENERGY ONTO A TARGET AT GREATER RANGES WARRANT EXPLORATION”
Unlike the 303, 7.62 NATO never vanished and remains in widespread use in support weapons such as sniper sys- tems and LMGs such as the FN MAG.
Throughout its history, assorted genuine and armchair experts have questioned the lethality of the 5.56 round, particularly when compared to the 7.62 NATO cartridge.
In original form, the 5.56 fired a 55-grain FMJ projec- tile at 3260 fps, delivering significant lethal effect through projectile velocity.
That was adopted by NATO in 1970, subsequently stan- dardised in 1980 with a 62-grain projectile at 3110 fps, de- livering somewhat better performance at long range and against body armour.
That’s still substantially less powerful than 7.62 NATO – 144-grain FMJ projectile at 2800 fps – but the big advan- tage of 5.56 was that a soldier could carry a lot – more than twice as many rounds for the same weight of 7.62.
A BRIEF EXPLANATION
For those unfamiliar with firearms, cartridge designations are a confusing mixture of metric, imperial, company, na- tionality, weight and even novelty descriptors.
For modern military cartridges, current practice is to in- dicate calibre and cartridge case length in millimetres – eg
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