When AR meets SCAR: The FN Arka – a potential replacement for the SA80 service rifle

As the hunt for the Armed Forces' replacement service rifle continues, the Arka, a new ambidextrous assault rifle from FN, could turn out to be a solid contender.

The MOD aims to replace the SA80 family of rifles under Project Grayburn, but arms manufacturers have been given few specific requirements about what exactly is needed from the new weapon.

As Defence Readiness and Industry Minister Luke Pollard pointed out back in April, Grayburn is currently in the concept phase – although a more detailed brief is rumoured to be coming out in the near future.

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Why vague may be valid for the MOD

In the meantime, companies like FN have been left somewhat in the dark about what the new rifle should be.

What level of accuracy is required? How heavy should it be? How long should it be? Does it need to be suppressed? What type of gas system should it have? Does it need a bayonet lug?

We do know the new weapon should be able to defeat body armour, but what level of armour and at what distance? And what does "defeated" mean? Punching through it or the ability to provide sufficiently accurate shooting - or volume of rounds - to reliably place a bullet between the plates?

And critically – in what calibre should the weapon be chambered? And off the back of that, what capacity magazine?

Perhaps this lack of a detailed brief from Defence Equipment & Support, the MOD's procurement arm, was deliberate.

Maybe the idea was to see what various companies would come up with on their own. This approach could end up delivering some inventive solutions to problems that hadn't even been considered.

Harking back

Let's go back to FN and the Arka – and then go even further back to the SCAR.

The FN SCAR – which stands for Special Operations Forces Combat Assault Rifle – was designed for the US Special Operations Command, entering service in 2009.

This family of weapons used a gas-operated short-stroke piston system. The Arka also uses this system, in which the propellant gas that's routed back to recock the weapon and eject a spent case is used to drive a piston which then interfaces with the bolt carrier assembly.

This keeps the working parts – and especially the breech – cleaner than direct impingement, in which the hot gas pushes directly on the bolt carrier.

This is the system used on the M16 and M4 carbine.

But gas system aside, those AR-style weapons did spur a design and control layout that's now become fairly common across Nato – and FN has built the Arka to reflect this.

Interoperability is a favourite word inside Nato – but it's also apt as it means someone used to shooting an M4 could easily switch to something like an HK416 – or an Arka.

This offers a significant advantage for Nato soldiers. Compare the weapon-handling and strip-down drills for an SA80 L85 with an M4, for example, and they are quite different.

But the Arka isn't just a copy of the AR, but improves on it.

The buttstock, for instance, is mounted to a hollow tube rather than the buffer tube of an AR because the recoil spring is not located there.

This means the rifle could take a folding stock, which is important for airborne forces and vehicle crews where space is at a premium. And of course the standard buttstock could be swapped for a force-specific or operator-preferred aternative.

One squaddie-friendly feature is the lack of a dust cover – and the need to constantly check you've closed it.

The bolt carrier assembly on the Arka is completely flat-sided, and FN argues this makes such a good seal with the ejector port that no dust cover is required.

An ambidextrous Arka

One of the main drawbacks of the SA80 is the fact that these weapons can only be shot right-handed from the right shoulder.

This is not only detrimental to left-handed firers, but to tactics too.

The best way to shoot behind cover is to expose as little of yourself as possible, and that's hard to do when trying to fire round the left-hand side of a building, wall or tree with a rifle in your right shoulder.

The Arka, in contrast, is fully ambidextrous, featuring the typical AR-style T-shaped cocking handle, and the magazine release and combined safety catch/change lever being mirrored on both sides of the weapon.

In terms of calibre, the Arka is currently available only in 5.56x45mm Nato, but can be offered in other chamberings.

At the platoon level, weapons like the L129A1 Sharpshooter and GPMG are in the much-loved 7.62x51mm Nato, with the SA80 being the standard 5.56x45.

And although forward infantry units of the US Army are operating M7 and M8 rifles in 6.8x51mm Common Cartridge, the smaller 5.56 is more widespread across Nato as a whole.

The US led the way with both 7.62 and 5.56, but it's far from certain whether 6.8 will become as common a cartridge as the name suggests.

In fact the US government has been working with FN on the 6.5x43mm cartridge, also known as the 264 Lightweight Intermediate Calibre Cartridge, which could also find its way into the Arka.

Sizing it all up

The Royal Marines currently operates two main individual weapons – the KS-1 and the SIG MCX – known by their British military designations as the L403A1 and L1433A1 respectively.

The KS-1 is used as a general assault rifle, while the shorter MCX is employed for Close Quarter Combat, such as boarding operations.

The Army, RAF and Royal Navy may have similar requirements of their individual weapons – Grayburn even outlines this – and these could be well met by the Arka, which is available in two barrel lengths.

With a CQC barrel measuring 285mm (11.25") and a standard barrel of 368mm (14.5"), these give the Arka overall lengths of 820mm (32.3") and 934.5mm (36.8") respectively with a fully extended buttstock.

I've shot the Arka in both configurations, and admittedly after only a relatively short range session – and with a suppressor fitted – found little to choose between them in terms of handling and felt recoil, which is fairly gentle anyway in 5.56.

With an empty 30-round magazine, the Arkas weigh in at 3.7kg and 3.9kg respectively, compared with 3.95kg for an SA80 L85 in the same configuration – an SA80 L85A2/A3 comes in at around 5.08kg with an optic and full mag.

While the SA80 L85A1 had plenty of well-documented problems, the A2 and A3 variants are genuinely fine rifles, but they come from a four-decdes-old design and while accurate, are not ambidextrous.

When Defence Equipment & Support comes out with more specific requirements for Project Grayburn, it's up to manufactuers like FN to build and offer their own vision of what the Armed Forces need.

But until then – we wait.