In September 2023, the United Kingdom has announced the selection of the Knight’s Armament Company KS-1 as the new individual weapon for the Ranger battalions and the Royal Marines Commandos. Back in January, while attending SHOT Show 2024, I was able to get a first hands on look at the new rifle which has been designated the L403A1. The requirement for the new rifle was released back in August 2021, as part of Project Hunter, and called for the “procurement and support of an Armalite Rifle (AR) platform Alternative Individual Weapon (AIW) System.”

Alternative Individual Weapon (AIW) System comprises the weapon and a ‘Signature Reduction System’ [suppressor] and an ‘Optic System’. The AIW replaces the SA80/L85 series of rifles and Colt Canada L119s in service with the Rangers and elements of the Royal Marines Commandos. After two years of competition the UK MoD announced that Knight’s KS-1 has been selected as the L403A1, beating off reported competition from Heckler & Koch’s HK416A5, SIG Sauer’s SPEAR-LT, Daniel Defense’s M4 and Glock’s new GR-115F.

The rifles will be procured via UK-based company Edgar Brothers and the £90 million ($110 million) contract will see up to 10,000 new rifles delivered over the next decade. An initial £15 million order for 1,620 AIW systems was placed with the first rifles delivered before the end of 2023. 

Anatomy of the L403A1 (Edgar Brothers)

The system is built around the Knight’s Armament Company KS-1 (SR-16) and includes the Knight’s QDC/MCQ-PRT suppressor, a magnified 1-10 LPVO optic from Vortex and an Aimpoint ACRO P-2 red dot, however, the rifle we examined had a Leupold DeltaPoint Pro mounted in its place. The rifle I had the chance to examine was in the configuration of L403A1 but did not have any markings unique to the British rifles which will likely have an ‘L number’ marking on the magazine well. On its left-side the rifle has ‘5.56mm KS-1’ on its upper receiver and bellow it on the lower receiver’s magazine well ‘STONER RIFLE [KAC’s roll mark] and [the weapon’s serial number]’. On the right side the magazine well is marked ‘SR-16 5.56mm, KNIGHT’s ARMAMENT CO. TITUSVILLE, FL, USA’. The weapon has the Knight’s URX-6 ML OK handguard.

The KS-1 is the latest iteration of the SR-16 series, it has a 13.7in (35cm) barrel, which if you look closely you can see is dimple cut to reduce weight. The rifle unloaded weighs in at 6.88lbs (3.1kg) and its overall length is 32.2in (82cm) with the stock collapsed and 34.2in (87cm) extended. The QDC/MCQ-PRT weighs an additional 13.9oz and adds just over 2 inches to the weapon’s length. The rifle uses a direct gas impingement system (or more correctly described as Stoner’s internal piston system). The rifle examined at SHOT Show was fitted with a Magpul SL-K Carbine Stock rather than the Magpul CTR which will equip the AIW. Similarly, it was equipped with Knight’s own Folding Micro Rear Sight rather than the Magpul MBUS Pro folding iron sights which the L403’s will be issued with.

The UK MoD required the rifle to have a removable trigger guard for cold weather use as the RM Commandos in particular regularly operate in cold weather environments, so Knight’s also designed a reinforced trigger guard, with a spring detent, that is more robust.

In terms of ergonomics and handling you can’t learn too much from handling an unloaded rifle for about 5 minutes but it felt fairly well balanced and had standard AR-15 type controls – including ambidextrous magazine and bolt releases. It had some heft to it (even unloaded) weighing approximately 4.3kg or 9.5lbs (after doing some maths adding up the stated weights for all of the AIW’s components: optics, suppressor, weapon). Which while heavier than a stock M4A1 it is lighter than an L85A2 and A3.

Special thanks to Knight’s Armament Company for allowing me to take a look at the rifle.

Check out our earlier article/videos looking at the AIW L403 here

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