VFC KAC L403A1 KS-1 Gas Blowback Rifle - Tan

In September 2023, after the two-year Project Hunter evaluation, the UK Ministry of Defence selected the Knight’s Armament KS-1 as the L403A1 — the new Alternative Individual Weapon for the Army Special Operations Brigade and the Royal Marines Commandos. It was chosen ahead of the HK416A5, SIG MCX-Virtus, Daniel Defense MK18 and Glock entries, and began reaching frontline units through 2024 and 2025. For UK milsim and impression players building a current Ranger Regiment or Commando loadout, this is the rifle.

VFC’s replica is licensed by Knight’s Armament and built on the KS-1 — the latest branch of the SR-16 family. It carries the full KAC Stoner Rifle markings on the lower, a 13.7″ dimpled heavy outer barrel under a near-full-length 12.8″ URX6 M-LOK handguard, and a B5 Systems Crane six-position stock. Construction is full metal with reinforced polymer furniture, and the controls are genuinely ambidextrous — selector, magazine release and bolt catch all mirrored, exactly as on the real rifle.

Mechanically it runs VFC’s current GBBR system with a snappy bolt cycle and real felt recoil through the buffer tube, fed by the VFC ‘EVO’ Next-Generation AR GBB hop unit with a steel TDC adjuster paired to a 330mm precision inner barrel. Out of the box it chronographs around 388 FPS on green gas with 0.20g — roughly 1.4 joules, so it will be over a 1J site cap: chrono it on the day and tune the gas, hop or valve to your site’s limit. It feeds from 30-round VFC GBBR M4 magazines, so an existing VFC mag collection drops straight in.

What’s on the outside

The external build is what sells the impression. The lower wears the full Knight’s Armament / Stoner Rifle trademarks; the 12.8″ URX6 M-LOK handguard runs almost the length of the 13.7″ dimpled barrel; the B5 Crane stock and reinforced polymer grip finish the current-issue look; and the whole rifle is in a correct Tan finish. The 14mm CCW muzzle thread takes standard airsoft suppressors and tracer units.

Specifications

Good to know before you buy

This is the base of an AIW impression, not the finished loadout — the real system pairs it with a Vortex 1-10 LPVO, an Aimpoint ACRO P-2, a KAC QDC suppressor and a Magpul sling. Browse our sights & optics and rifle accessories to build it out.

It is also sold in two-tone, VCRA-exempt colourways as separate listings — if you can’t meet the UKARA/defence requirement for a full RIF, ask us about those. Magazines are 30 rounds, so pick up spares if you run mid-length games.

Frequently asked questions

Do I need UKARA to buy this?
Yes. The Tan version is a realistic imitation firearm (RIF), so a UKARA entry or another recognised defence is required — we check it at the point of sale. The two-tone versions are VCRA-exempt and do not need it.

What gas does it use, and can it run HPA?
Green gas (top gas) as standard. It can also be run on HPA using a GBBR magazine adapter and an external regulator if you prefer.

What FPS is it, and is it site-legal?
It chronographs around 388 FPS on green gas with 0.20g — about 1.4J, which is over a 1J cap. Chrono it on the day and tune the gas, hop or valve to meet your site’s limit.

Which magazines fit?
VFC GBBR M4 magazines (30 rounds). Existing VFC GBBR M4 mags drop straight in without modification.

UKARA: As a realistic imitation firearm, this product requires UKARA registration or a valid defence. We verify at checkout. Register by playing 3 games over 56+ days at Skirmish Wycombe Airsoft.