Specna Arms SA-F04-RL FLEX™ Gen.2 HAL¹ M4 AEG – Black

The Specna Arms SA-F04-RL FLEX™ Gen.2 HAL¹ M4 AEG bridges reliability and tactical versatility for UK airsoft players who demand a rifle that adapts to multiple engagement styles. Built on a proven platform with thoughtful engineering, this carbine balances weight, accuracy, and field durability without premium pricing.

Key Features

• HAL¹ Electronic Trigger Unit – programmable fire modes (safe, semi, full auto, custom burst) for tactical flexibility
• Rotary hop-up system – precise BB trajectory adjustment over range
• Alloy outer barrel and receiver components – lightweight yet rigid, reducing fatigue during extended play
• M-LOK rail compatibility – modular accessory mounting on 20mm RIS/RAS handguard
• Steel mock bolt carrier and QD sling sockets – authentic AR-15 ergonomics and quick-deploy capability
• Sliding, multi-position stock – adaptable to player frame size and CQB/outdoor transitions
• Includes 380-round high-capacity magazine – ready-to-play out of the box

Real-World Use Cases

This rifle excels in mixed-terrain skirmishes where you need rapid mode switching—engage at distance in semi-auto, reposition under covering fire in full auto. The lightweight alloy build suits mobile milsim roles (squad leader, scout) without causing shoulder fatigue. The M-LOK rail system lets you mount optics, grips, and tactical lights without specialist knowledge, making it ideal for players customising their setup mid-campaign. The programmable ETU is a standout for team-based play, where burst or preset semi-only modes can enforce gameplay rules.

Technical Specifications

• Velocity: 310 fps (0.20g BB)
• Gearbox: V2 (M4-pattern)
• Motor: Standard (fixed-speed brush motor)
• Hop-up: Rotary
• Battery: 7.4V Deans connector (Li-Po compatible)
• Magazine capacity: 380 rounds (high-capacity wheel-wound)
• Magazine compatibility: Standard AEG, high-capacity, wheel-wound
• Overall length: 670mm
• Weight: 1.93 kg (unloaded)
• Firing modes: Safe, semi-automatic, full automatic, programmable
• Colours: Black, Half-Tan

Compatibility & Upgrades

The V2 gearbox is one of the most widely supported platforms in airsoft; upgrade parts (springs, gears, cylinders) are readily available from UK retailers. The 20mm RIS/RAS rail accepts standard Picatinny optics, scopes, and foregrips. The rotary hop-up works with most airsoft BB weights, though 0.28g to 0.32g is recommended for outdoor range. The 7.4V Deans connector pairs with affordable LiPo packs; upgrading to an 11.1V battery will increase fire rate, though ensure ETU firmware supports higher voltages. M-LOK attachments (angled foregrips, sling mounts) are plug-and-play.

UK Legal & Site Notes

All Specna Arms AEGs are two-tone (receiver, buffer tube, or outer barrel painted) to comply with UK law unless your site is RIF-registered. This model ships ready to use. Always check your local site’s FPS limits—310 fps is field-legal at most UK venues, but some CQB sites cap at 280 fps. Carry in a skirmish bag to and from play. The included magazine is high-capacity; some woodland sites restrict these to semi-auto only, so check event rules. Ear protection and eye pro are essential.

Ready to upgrade your loadout? The Specna Arms SA-F04-RL FLEX™ Gen.2 is in stock now. Add it to your basket, select your colour, and pair it with a quality optic or barrel extension to suit your role. Contact our team if you need battery, magazine, or upgrade advice.