Back in 2021, the UK’s Ministry of Defence embarked upon an ambitious programme to equip its special forces with a new rifle – arguably a soldier’s most important tool. Through its Defence Equipment & Support (DE&S) division, the British Army set about the procurement and support of an Armalite Rifle (AR) platform, known as the Alternative Individual Weapon (AIW) System.

The requirements were clear from the start. The rifle system needed to comprise the weapon, a suppressor and a new optics system. Furthermore, the gun had to be gas operated with a rotating, locking bolt – and had to feature a standard configuration with the magwell in front of the trigger housing, rather than a bullpup design, in which the firing grip is located in front of the weapon’s breech.

Three years on, an initial £15m order for 1,620 AIW systems has just been placed, with the army leaving open the option to purchase up to 10,000 rifles, at a cost of £90m, over the next decade. The chosen model is the recently unveiled L403A1, which will become the primary weapon of the elite Royal Marine Commandos. Both stealthier and deadlier than older models, it is a refinement of the Knight’s Stoner 1 (KS-1) rifle, manufactured by the US-based Knight’s Armament Company (KAC).

The KS-1 is the end result of 40 years of work refining the AR-15 rifle, and KAC has incorporated the latest materials and manufacturing methods into an innovative design and engineering process. The rifle was designed with the clear intention to meet or even surpass the current needs of highly specialised military units, including elite special forces, to ensure that they are equipped to deal with a rapidly evolving range of threats in diverse theatres of operation.

The L403A1 is designed to get away from the inefficiencies of the old SA80 bullpup design. Image Credit: UK MoD Crown copyright 2023

The 5.56mm weapon – designed in the style of the popular AR-15 – is intended to provide increased lethality through improvements in both accuracy and reliability. Procured through open competition, as specified by UK government regulations, this model emerged as the preferred candidate, having met the stringent conditions for use alongside current in-service systems. Just as importantly, the new rifle was designed to fit the needs of the Army Special Operations Brigade (ASOB), which operate in high-threat environments.

Project Hunter – as the AIW procurement programme was named – was run as part of the DE&S Dismounted Close Combat (DCC) Portfolio. “Thanks to a successful collaboration between DE&S, the Army SoldierWorks team, ASOB and our industry partners, Project Hunter has delivered a game-changing rifle at great pace,” says Colonel Paul Cummings, head of the dismounted close combat portfolio at DE&S. “Through clear, concise engagement, the Project Hunter team was able to set a demanding but achievable timeline for industry to respond to.”

Hitting the target

The L403A1 rifle is merely the central element in a package that includes other next-generation systems – all to increase force effectiveness. Perhaps most notable here is a magnified 1-10 LPVO Vortex optic, as well as the Aimpoint ACRO P-2 red dot, which both help bolster accuracy.

“Project Hunter offers a marked increase in lethality and has delivered one of most capable day-sights currently available,” says Brigadier Robert Hedderwick, ASOB’s commander. “Importantly, the weapon system will be further enhanced by our newest generation of night optics. The rifle will enable seamless integration and interoperability, which is essential given our specialist role, and the importance of working alongside many of the UK’s allies.”

The fanfare around the new weapons system is testament to the success of Project Hunter, the programme put together to assess and test candidates for the AIW, which replaces the SA80/L85 series of rifles and the Colt Canada L119s currently used by both the Ranger Regiment and some units within the Royal Marines Commandos. It will also complement the L85A2 and L85A3, which currently arm the majority of units in the UK armed forces.

The new weapon shares many commonalities with other Nato allied forces, with interoperability a key consideration in its design. Image Credit: UK MoD Crown copyright 2023

The KS-1 is the latest version of the SR-16 – a popular series of lightweight, gas-operated, magazinefed, air-cooled, shoulder-fired weapons produced by KAC. It has a 13.7in (35cm) barrel, and an overall length of 32.2in (82cm), which increases to 34.2in (87cm) when the stock is extended. Experts suggest that, in the testing phase, the updated KS-1 system (now designated L403A1) came out ahead of options from Heckler & Koch, SIG Sauer and Glock, among other defence giants.

Project Hunter – through the Dismounted Close Combat (DCC) team, within the DE&S Soldier, Training & Special Programmes (STSP) group – drew on its long-standing collaboration with its preferred UK distributor, Macclesfield-based company Edgar Brothers. The Cheshire manufacturer, for its part, partners with KAC from across the Atlantic. The company will also source and assemble the accessories that will come with the AIW. There are plenty of examples here, including an easy-release Magpul sling; a small and powerful light fixture from Surefire; a high-strength angled foregrip; and grip and heat protection solutions from RailScales.

Through this relationship with Edgar Brothers, DE&S estimates that it has generated almost £500,000 in efficiencies, as well as delivering a new ASOB weapons system in less than two years. “By engaging with the ASOB from the start, we were able to tailor the testing and acceptance process to exactly what was needed, saving considerable time,” Cummings explains. “At all stages, the team drove concurrent, rather than sequential, activity and were proactive in marshalling the project through the approvals process to promptly move it to contract award.”

The engineering team’s testing and evaluation stages, which involved countless wet and windy mornings at firing ranges, and working alongside members of the ASOB to capture technical data that would inform the contender selection process, helped successfully steer Project Hunter to completion.

“I joined the project during the assessment phase, just before the project trials were due to take place,” remarks Chanel Ebanja, the soldier, training and special programmes manager at DE&S. “The thorough testing and evaluation, and the removal of contender systems at their point of failure, saved us both time and resources.”

Armed for allied operations

The AIW is markedly different in design to the SA80 that British forces have used for so long. The specific requirements for its replacement – moving as it does away from the bullpup design – is a nod to one of the perceived inefficiencies of the SA80, which has been criticised in the past for plastic housing that is easily damaged, magazine release catches that can be activated accidentally, and a tendency for gas mechanisms to pop open erratically.

Taken together, AIW is clearly intended to be a more robust, reliable and accurate weapons system. But the selection of the KS-1 was not based solely on the rifle’s straightforward performance. Rather, it’s vital that any upgrade in weaponry made by British forces should complement the equipment used by its allies.

As the L403A1 is an ArmaLite Rifle system, it happily shares many common features with systems used by other Nato members, and indeed DE&S identified interoperability as a key criterion in the selection process. In the crucial role of working with friendly forces, it allows ASOB to use the platform to more efficiently share skills and drills.

Equally important is the appreciation that upgrading a single weapons system will not, in itself, constitute a major improvement in force effectiveness. Indeed, the AIW is just one component in a larger campaign to scale up the capability of elite British forces. For example, the Royal Marine Commandos, among the first to adopt the AIW, are in the process of upgrading their systems across the board. As well as a new rifle, next-generation night vision goggles, tactical communications systems, battlefield vehicles and helmets are just some of the components included in this major refit – aimed at ensuring the Royal Navy’s elite force remains in a high state of readiness.

For its part, the so-called ‘Commando Force Programme’ will deliver tangible change across all areas of amphibious operations. A new helmet, made by Gentex, is a key component here, as is a new range of night vision binoculars, produced by L3Harris. Among other things, this kit should yield major advantages in night-time littoral operations, as well as boarding missions and other battles in confined spaces.

But this is still just one part of a much broader campaign – of which a new long-term procurement phase is scheduled to start this year. Across the board, in short, several wings of the British military are working hard to gain a decisive edge on the battlefield, and the AIW represents one of the cornerstones of this strategy.

KAC KS-1 vital stats

  • Base model: KAC KS-1
  • Barrel length: 13.7” (34.8cm)
  • Calibre: 5.56mm
  • Weight: 6.88lbs/3.12kg
  • Overall length: 32.2” (81.8cm) to 34.2” (86.9cm)