Specna Arms SA-F04-RL FLEX™ Gen.2 HAL¹ ETU M4/AR-15 AEG

If you’re looking for a primary that weighs nothing but is built like a tank, the Specna Arms SA-F04-RL FLEX™ HAL¹ ETU M4/AR-15 AEG will suit you perfectly! Part of Specna’s FLEX™ line, this M4/AR-15 replica is constructed almost entirely from high-density polymer with an alloy outer barrel, keeping the build lightweight and agile, not to mention cost-effective. As with previous FLEX™ releases, the SA-F04-RL is equipped with a 6.03mm tightbore inner barrel, straight out of the box, providing a free upgrade to keep this lightweight and agile platform competitive with rivals.

Inside, we are treated to advanced functions via the HAL¹ ETU/MOSFET system. The HAL¹ ETU offers binary trigger, AUG mode and sniper delay instead of semi-auto and semi-auto lock, 3-round burst or 5-round burst instead of full auto, along with several quality-of-life improvements and, most importantly for CQB, adjustable pre-cocking! Pre-cocking positions the piston at the rear of its cycle after a shot, meaning when you pull the trigger, the response is practically instantaneous, ideal for semi-auto duels in the close confines of a CQB site.

Starting at the tip of the 8.5-inch outer barrel, we can find an M4/AR-15 birdcage flash hider mounted to 14mm CCW male threading. The outer barrel is constructed from alloy to provide a strong backbone and keep the tightbore inner barrel nice and straight for perfect accuracy. If you want to mount a tracer unit, suppressor or alternative muzzle device, all you need to do is unscrew the flash hider and mount your preferred device, thanks to the common 14mm CCW threading at the tip of the barrel.

The handguard is equipped with M-LOK negative space attachment slots at the 3, 6, and 9 o’clock positions, ready for any M-LOK accessories to be directly mounted. M-LOK is one of the latest accessory interfaces to hit the market, both for real steel and Airsoft, allowing you to fit M-LOK vertical or angled grips directly, or mount 20mm Picatinny rail adapters for M-LOK to make use of 20mm Picatinny grips, flashlights and laser units.

Also present on each side of the handguard is a pair of QD sling sockets; one at the front and a second at the rear. This allows you to fit QD sling swivels, meaning you can quickly remove your sling and reconfigure it without needing to untangle yourself! The QD sockets are available on either side, meaning both left and right-handed shooters can mount a sling setup to suit them with ease.

With a 20mm Picatinny rail at the 12 o’clock position, the handguard also provides a mounting point for the included flip-up aperture iron sights, which can either be left flipped down or removed entirely if you prefer to use a red dot sight or scope. The irons can be raised and lowered by hand, with no need to press buttons or fiddle with catches, and are fully adjustable for both windage and elevation.

The handguard’s upper Picatinny rail meets the 20mm rail on the receiver seamlessly, allowing large optical sights and red dot sights and magnifier combos the extra space they need to be mounted easily. The receiver itself is constructed from fibre-reinforced high-density polymer with a beautiful matt finish and a high-quality textured feel, keeping the weight low and the strength high, with added scratch resistance so the odd mid-skirmish bump or scrape doesn’t mean your pride and joy looks scruffy.

The receiver itself is a unique Specna Arms design, derived from the SA-FX01 AR-9 but compatible with standard M4/AR-15 AEG magazines. The whole receiver has been given a touch of modernity inspired by modern “billet” receivers for real steel AR-15 rifles, with weight reduction on either side and grooves on the front of the magazine well. These grooves provide a gripping position for unconventional shooting stances, allowing you to control the front end of the SA-F04-RL when engaging in tight quarters.

As with standard AR receivers, the charging handle is located at the top rear. When pulled rearwards, the handle retracts the mock bolt carrier on the right side, providing access to the rotary HOP-up adjuster. The rotary HOP-up unit is the latest design for the M4/AR-15 platform and improves on the older “gear” unit with finer increments of adjustment and improved ability to hold its setting under the vibrations of full auto fire.

The HOP-up allows the user to adjust the amount of backspin applied to the BB and tune it to provide optimum range and a stable flight path with various weights of BBs. For the SA-F04-RL, we recommend 0.25g BBs for the best combination of projectile speed, wind resistance, and range. When you have adjusted your HOP-up, you can press what is known as the “bolt catch”, the ping-pong paddle-shaped control on the right side of the receiver. This will release the mock bolt carrier and send it forward with a satisfying clank, keeping dust and debris out of this sensitive internal part, even if you like the odd mud bath at your local woodland site!

The magazine release is ambidextrous, with an enlarged button on the right side and a smaller button on the left, ideal for both left and right-handed shooters. The fire selector is also ambidextrous and a unique modern design, offering 3 modes of fire: safe, semi-automatic and fully automatic, with a 90-degree throw between each mode. The HAL¹ ETU also allows the fire modes to be programmed, a very nifty feature in a platform at this price point!

Moving down, we come to the pistol grip, which boasts a refined grip angle for greater comfort when shooting with the stock fully collapsed and in more modern shooting stances. Each flank of the pistol grip includes fine crackle texturing, with additional linear texture on the front and back straps for perfect wet-weather handling. The trigger guard is built into the receiver to improve strength and is enlarged to allow for gloved users. The trigger is a flat design, ideally suited to rapid semi-automatic fire with the pre-requisite modern aesthetic.

At the rear of the receiver, we come to the M4/AR-15 buffer tube, which is constructed from high-density polymer and offers 6 positions of adjustment so you can adjust the stock to suit your body type and loadout perfectly. The buffer tube also serves as the battery compartment, and to access the battery compartment, you will need to pull the adjustment pin of the stock out slightly (located on the bottom of the stock). With the pin held in this position, you can slide the stock off the buffer tube to the rear, revealing a Deans battery connector inside. We recommend a 7.4V 1450mAh LiPo in stick configuration for the SA-F04-RL for an easy fit and perfect performance.

Bringing up the rear of the SA-F04-RL, we have the Specna Arms Light Ops stock, which is part of Specna’s new SAAS (Specna Arms Accessory System) line. This stock is based on existing low-profile M4/AR-15 stocks but with some choice refinements for improved comfort. The cheek piece of the stock is cylindrical, avoiding potential snags and has rubberised sections on either side with Specna Arms “SA” texture to provide a positive and comfortable cheek weld.

The butt plate is constructed entirely from rubber with deep linear serrations and an angled profile to more effectively grip your shoulder if you use Airsoft body armour or a bulky tactical vest. Either side of the stock boasts QD sling sockets, meaning if you add a QD sling swivel, you can add and remove your sling in a matter of seconds or less. The low-profile adjustment lever of this stock is well out of the way and immune to snags, and has texture on its surface to allow for ease of use in wet conditions. This stock not only looks unique but functions fantastically, and the solid high-density polymer it is constructed from feels like it could be used to beat whales to death.

Inside the Gen.2 SA-F04-RL, we are treated to the Aether-enhanced gearbox shell, the same reinforced V2 shell used in Specna’s top-tier PRIME series. The Aether features a reinforced spine and ports throughout the design to allow for easy tuning, ideal for the techy types. Also inside are 18:1 ratio steel gears running on 8mm bushings. The spring guide is an ESA quick-change example, making power tuning a breeze for those who want to get as close to site limits as possible. The inner barrel is a 6.03mm tightbore paired with the Magnus TDC rotary HOP-up unit, giving you superb accuracy potential and the most up-to-date HOP-up unit style for M4/AR-15 AEGs. All internal parts are Tokyo Marui AEG spec, meaning aftermarket upgrades are a go for the performance seekers!

The HAL¹ ETU adds a whole lot of functionality into the mix, with programmable fire controls, 6 levels of pre-cocking adjustment and 5 levels of trigger sensitivity adjustment. Available fire modes include 3 or 5-round burst, binary trigger, AUG mode, aka two-stage trigger, semi-auto only and sniper delay, giving you loads of options for how you use your SA-F04-RL. Features like these are usually only present in high-end replicas; we simply cannot believe the wealth of functionality inside this rifle, especially considering the price!

If an affordable CQB platform is on your to-buy list, the Specna Arms SA-F04-RL FLEX™ Gen.2 HAL¹ ETU M4/AR-15 AEG is the one to go for! Packed with impressive internals and mission-ready on the outside, the SA-F04-RL is a uniquely player-friendly build for a fantastic price!

Features

• 6.03mm Tightbore inner barrel – Great accuracy and range potential
• High-density polymer construction – Alloy outer barrel and flash hider, alloy and steel trim parts
• 14mm CCW Male threaded outer barrel – Ready for a tracer unit or suppressor
• M-LOK handguard – M-LOK slots at 3, 6, and 9 o’clock, 20mm up top, ready for M-LOK or 20mm accessories
• 4 QD sling sockets on the handguard, 2 on the stock – Ready for QD sling swivels to be mounted
• Flip-up aperture iron sights pre-installed – Adjustable for windage and elevation, 2 apertures to choose from
• 20mm Picatinny railed receiver – Ready for red dot sights, PEQ lasers or scopes to be mounted
• Rotary adjustable HOP-up unit – The latest M4/AR-15 design, holds its setting well and allows for fine adjustment
• Ergonomic pistol grip – Textured with a filled-out back strap, a more vertical design for modern shooting stances
• Flat “Milspec” trigger guard – Standard M4A1 military style guard
• 3-Position fire selector switch – SAFE, SEMI AUTO & FULL AUTO, 90-degree throw between each mode
• Extended charging handle – Fast access to the HOP-up unit for quick mid-game adjustment
• Functional mock bolt catch – Send the mock bolt home after HOP-up adjustment by hitting the bolt catch
• 6-Position M4/AR-15 buffer tube – Adjust the stock quickly and easily to suit your body type or loadout
• Specna Arms Light Ops stock pre-installed – Comfortable and modern stock design with QD sling sockets built-in
• Version 2 Aether™ Gearbox:
  • Aether Enhanced gearbox shell
  • Aether Aluminium nozzle
  • Polymer piston with steel tooth rack
  • 8mm Bushings
  • ESA quick-change spring system
  • Steel 18:1 ratio gearset
• HAL¹ Programmable MOSFET/ETU functions:
  • 3 or 5-round burst
  • Binary Trigger
  • Semi-auto only
  • Sniper delay
  • Two-stage trigger (AUG mode)
  • Adjustable pre-cocking (6 levels)
  • Active braking
  • Low-voltage alarm
• HAL¹ Programming instructions
• Rear wired – Deans battery connector inside the buffer tube, accessible with the stock removed
• Recommended battery: 7.4V 1450mAh LiPo battery in stick configuration
• Compatible with M4/AR-15 AEG magazines – Recommended Mags: Specna Arms S-MAG Mid-cap

Package Include

• Specna Arms SA-F04-RL FLEX™ Gen.2 HAL¹ ETU M4/AR-15 AEG
• 380rnd High-capacity magazine

Specification