Specna Arms SA-F03 FLEX™ Gen.2 M4/AR-15 Compact AEG; HAL¹ ETU

Specna Arms
Code: SPE-01-048384-00
£154.99
  • High-density polymer construction
  • 6.03mm Tightbore inner barrel
  • Gen.2 - Magnus™ HOP-up, Aether™ gearbox shell

This rifle is a great budget option, partly resembling the new British military rifle, the L403A1/KS-1. It has a polymer handguard and receiver, keeping the weight low. This is perfect if you are new to Airsoft or prefer a more agile style of gameplay, and a hefty, realistic Airsoft platform will just weigh you down.

Specna's FLEX™ Gen.2 pushes the featureset of affordable AEGs up a notch or two, equipped with the Aether™ enhanced gearbox shell and Magnus™ TDC Rotary HOP-up unit from the PRIME™ series. Also on board is the Aether™ CNC aluminium nozzle and Helium™ HOP-up bucking, boosting accuracy and range considerably.

If you need a lightweight but advanced backup, the Specna Arms SA-F03 FLEX™ Gen.2 HAL¹ ETU M4/AR-15 AEG has both boxes ticked!

Full description

Description

The Specna Arms SA-F03 is 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-F03 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.

Starting at the tip of the 10-inch outer barrel, we can find a birdcage flash hider pre-installed, the classic M4/AR-15 muzzle device. The flash hider looks great and suits the build well, but can be replaced with any other 14mm CCW threaded muzzle device if you prefer a different style, including tracer units and suppressors.

The handguard is equipped with M-LOK negative space attachment slots at the 3, 6, and 9 o'clock positions, punctuated with additional M-LOK slots at the offset angles, giving you plenty of space to mount M-LOK accessories. 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.

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 pressing the textured button at the rear and are fully adjustable for both windage and elevation.

As we arrive at the receiver, we see a familiar sight: M4/AR15 controls, with a well-placed fire selector sitting beneath a right-handed shooter's thumb, a dummy bolt catch in the centre of the receiver on the left side, and the magazine release, which is located on the magazine well on the right side of the AEG. While the controls on the SA-F03 are set up for right-handed users, they can also be operated by a left-handed user without issue after a bit of practice.

The fire selector provides 3 modes of fire: SAFE, SEMI and AUTO, which are denoted by recessed text surrounding the fire selector lever. Each fire mode has a 90-degree throw between, making it super easy to switch from SAFE to SEMI as you bring the AEG up and align the sights.

The magazine release is on the right side of the magazine well, protected by a moulded-in "fence" which protects the release from inadvertently being pushed as your rifle brushes against your kit. This is a push-through mag release, which is easily operated using the trigger finger, one of the enviable handling characteristics the AR-15 platform is known for.

The charging handle can be found at the top rear of the receiver and features an extended latch which protrudes on the left side for fast access and one-handed operation. When the charging handle is pulled, the dust cover on the right side will open, and the mock bolt carrier will retract, revealing the rotary HOP-up unit within.

This device 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-F02, we recommend 0.25g for the best combination of projectile speed, wind resistance, and range.

The pistol grip provided on the SA-F03 is an "A2" finger ridged type, with diamond checkering on either side and linear grooves on the rear to provide a positive grip. The A2 grip finds its way onto many M4/AR15 AEGs, primarily due to its classic looks and its suitability for a variety of hand types. This grip has a nice, large motor adjustment screw, which is great to see, as more affordable replicas often use a small grub screw for this role, which we have often found to be inadequate.

The SA-F03 also uses the M4/AR15 modular trigger guard system, allowing the trigger guard to be changed out for an enlarged one, as long as the replacement guard is of AEG spec. The pre-installed trigger guard is a standard M4A1 flat type, made from polymer to keep the build lightweight.

Moving to the rear, we can find a 6-position M4/AR15 buffer tube, constructed from the same high-density polymer as the receiver. This keeps the build light and prevents your buffer tube from becoming worn from constant stock adjustments, which often removes the finish on metal buffer tubes and makes them look tatty.

The stock runs on this buffer tube and can be adjusted to any of the 6 positions by holding down the textured adjustment lever on the bottom of the stock and adjusting it to the desired length. On either side of the stock, we can find QD sling sockets, which, when coupled with a QD sling stud, can provide a flexible sling setup with quick-release functionality.

Bringing up the rear of the SA-F03, 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-F03, 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-F03.

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 you need a cheap and reliable Airsoft rifle, the Gen.2 series from Specna Arms is an ideal choice. They come with reliable internal parts and a solid yet lightweight build ready for skirmishing. If you're after a military-inspired look ready for attachments, the Specna Arms SA-F03 FLEX™ Gen.2 HAL¹ ETU M4/AR-15 AEG is a great choice!

Features

  • High-density polymer build - Alloy outer barrel, steel trim parts
  • 6.03mm Tightbore inner barrel - Great accuracy potential
  • 14mm CCW male threaded outer barrel - Tracer/suppressor ready
  • QD sling sockets on board - On each side of the stock
  • M-LOK Handguard - M-LOK slots at 3, 6, & 9 o'clock, ready for M-LOK accessories
  • 3x 20mm Picatinny rails for M-LOK pre-installed - Use 20mm Picatinny accessories
  • Extended charging handle - Easier HOP-up access for gloved shooters
  • "A2" Finger ridged pistol grip - Comfortable for a wide variety of hand sizes
  • M4/AR-15 Flat trigger guard - Interchangeable with aftermarket M4 AEG trigger guards
  • 6-Position M4/AR-15 buffer tube - Adjust the stock to suit your body type and loadout
  • Specna Arms Light Ops stock pre-installed - Comfortable and modern stock design with QD sling sockets built-in
  • Rear wired: Deans connector - Recommended battery: 7.4V 1300 mAh LiPo battery
  • 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 Includes

  • Specna Arms SA-F03 FLEX™ Gen.2 HAL¹ ETU M4/AR-15 AEG
  • 300rnd Hi-Capacity Magazine

Specification

General

Weapon Construction External
Platform Type
Assault Rifle
Over 18 Only Icon
Over 18
Yes
Icon UKARA - United Kingdom Airsoft Retailer Association
Defence / UKARA Required
Yes, No,
Screwdriver Icon
Prebuilt
Yes
Package
Included Items
Magazine
Skill Level Icon
Skill Level
Beginner Player
Patrol Base - Warning Icon
Warnings
Li-Po - Never Leave Charging Unattended
Li-Po - Only Use Approved Chargers
Li-Po - Charge in a Fire Safe Area

Testing

FPS Icon
FPS, using 0.20g BBs
Approx.325fps ± 10%, using 0.20g BBs

Weight and Dimension

Weight KG Icon
Weight (KG)
Approx.2.1KG
Weapon Length Collapsed
Length
71cm
Weapon Length Extended
Length (Extended)
79cm

Construction

Colour Wheel Greyscale
Primary Colour
Black,
Half-Tan
Half-Tan
,
Foliage Green,
Construction Icon
Construction
Alloy outer barrel, flash hider & trim parts. High density polymer receiver, handguard, buffer tube, pistol grip & stock. Steel dust cover & body pins.

Weapon Specific

Power Source Icon
Powered By
Electric
Platform
Platform
Assault Rifle, M4 / AR-15 / M16, M4/AR-15 AEG,
Fire Select Icon
Fire modes
PatrolBase | Fire Select Safe
Safe
Patrol Base | Fire Select - Semi Automatic
Semi Automatic
Patrol Base | Full Automatic
Full Automatic
Programmable
Weapon Safety Features Icon
Safety Features
Trigger Disconnect
Shooter Configuration Icon
Shooter Configuration
Right Handed
Weapon Configuration Icon
Platform Configuration
Standard
Weapon Scale Icon
Platform Scale
1:1
Suggested BB Weight
Suggested BB Weight
0.25g

Hop-Up

Hop-Up Unit Adjuster Icon
HOP-Up Adjuster Type
Rotary
Hop-Up Unit Location Icon
HOP-Up Adjustment Location
Behind the mock bolt carrier, accessible with the charging handle pulled and held back.

Furniture

Weapon Furniture Icon
Furniture
  • Railed Handguard
  • Railed Receiver
  • Ergonomic Pistol Grip
  • AR Buffer Tube
  • Flip-Up Ironsights
  • Bird Cage Flash Hider
  • Threaded Outer Barrel
  • QD Sling Point
  • Enlarged Trigger Guard
  • Extended Charging Handle
  • M-LOK Handguard
  • M-LOK Picatinny rails x 3
  • Rubber butt plate
  • Specna Arms Light Ops Stock
Rail System Icon
Rail System
20mm RIS / RAS, Pre-installed 20mm Picatinny rail sections for M-LOK, 20mm Railed Receiver, M-LOK,
Icon Stock Positions
Stock Type
Sliding, Multi-Position,
Weapon Length Extended
Stock Positions
6
Sight Type Icon
Sight Type
Aperture Iron Sight
Sling Plate Icon
Sling Options
Stock, QD, Loop,

Barrel

Outer Barrel Length (in)
10''
Icon Thread Type
Outer Barrel Thread Type
Male
Icon Thread Direction
Outer Barrel Thread Direction
CCW (Counter Clockwise)
Outer Barrel Thread Size
Outer Barrel Thread Size
14mm
Inner Barrel Diameter
Inner Barrel Diameter
6.03mm
Inner Barrel Length
Inner Barrel Length
280mm

Magazine Specific

Magazine Type
Magazine Type
AEG, High Capacity,
Magazine BB Capacity
Magazine BB Capacity
Approx. 300 Rounds

Electric Gun Specific Information

Gearbox
Gearbox Icon
Gearbox Version
V2 Gearbox
Wiring Icon
Gearbox Wiring
Rear Wired
Spring Change Icon
Gearbox Quick Change Spring
Yes
Digital Trigger Icon
Gearbox Electronic Trigger
Yes
Motor
Airsoft Motor Icon
Motor Type
Standard
Battery Specific
Battery Voltage
Battery Voltage
7.4V
Battery Connector
Battery Connector
Patrol Base | Icon | Deans
Deans

Size guide

Joule Charts

Special Instructions

These table can be used as a reference to see if the BB weight you are using will be over acceptable Joulage limits at some Airsoft Sites in the UK. To check if the weight can be used chrono your weapon using the BB you intend to use, and then compare it to the chart.

FPS, Power and Joule Limits can vary from site to site, so please get in touch with where you're going to play with in advance to avoid disappointment.

Suggested limits are based on Joulage Limit rules used Halo Mill: Proving Grounds, with a 350fps limit for Automatic Replicas, 400fps for Semi-Automatic Replicas, and 500fps for Bolt Action Replicas.

Tap the tabs below to open the relevant chart for your replica.

Suggested limits are based on Joulage Limit rules used Halo Mill: Proving Grounds, and is the equivalent of 350fps, using 0.20g BB resulting in an upper limit of 1.14j.

Velocity BB Weight (Grams)
FPS 0.20 0.25 0.28 0.30 0.32 0.36 0.40 0.43 0.45 0.50
250 0.58 0.73 0.81 0.87 0.93 1.05 1.16 1.25 1.31 1.45
260 0.63 0.79 0.88 0.94 1.00 1.13 1.26 1.35 1.41 1.57
270 0.68 0.85 0.95 1.02 1.08 1.22 1.35 1.46 1.52 1.69
280 0.73 0.91 1.02 1.09 1.17 1.31 1.46 1.57 1.64 1.82
290 0.78 0.98 1.09 1.17 1.25 1.41 1.56 1.68 1.76 1.95
300 0.84 1.05 1.17 1.25 1.34 1.51 1.67 1.80 1.88 2.09
310 0.89 1.12 1.25 1.34 1.43 1.61 1.79 1.92 2.01 2.23
320 0.95 1.19 1.33 1.43 1.52 1.71 1.90 2.05 2.14 2.38
325 0.98 1.23 1.37 1.47 1.57 1.77 1.96 2.11 2.21 2.45
328 1.00 1.25 1.40 1.50 1.60 1.80 2.00 2.15 2.25 2.50
330 1.01 1.26 1.42 1.52 1.62 1.82 2.02 2.18 2.28 2.53
335 1.04 1.30 1.46 1.56 1.67 1.88 2.09 2.24 2.35 2.61
340 1.07 1.34 1.50 1.61 1.72 1.93 2.15 2.31 2.42 2.68
345 1.11 1.38 1.55 1.66 1.77 1.99 2.21 2.38 2.49 2.76
350 1.14 1.42 1.59 1.71 1.82 2.05 2.28 2.45 2.56 2.85
355 1.17 1.46 1.64 1.76 1.87 2.11 2.34 2.52 2.63 2.93
360 1.20 1.51 1.69 1.81 1.93 2.17 2.41 2.59 2.71 3.01

Suggested limits are based on Joulage Limit rules used at Halo Mill: Proving Grounds, and is the equivalent of 400fps, using 0.20g BB resulting in an upper limit of 1.49j.

Velocity BB Weight (Grams)
FPS 0.20 0.25 0.28 0.30 0.32 0.36 0.40 0.43 0.45 0.50
250 0.58 0.73 0.81 0.87 0.93 1.05 1.16 1.25 1.31 1.45
260 0.63 0.79 0.88 0.94 1.00 1.13 1.26 1.35 1.41 1.57
270 0.68 0.85 0.95 1.02 1.08 1.22 1.35 1.46 1.52 1.69
280 0.73 0.91 1.02 1.09 1.17 1.31 1.46 1.57 1.64 1.82
290 0.78 0.98 1.09 1.17 1.25 1.41 1.56 1.68 1.76 1.95
300 0.84 1.05 1.17 1.25 1.34 1.51 1.67 1.80 1.88 2.09
310 0.89 1.12 1.25 1.34 1.43 1.61 1.79 1.92 2.01 2.23
320 0.95 1.19 1.33 1.43 1.52 1.71 1.90 2.05 2.14 2.38
330 1.01 1.26 1.42 1.52 1.62 1.82 2.02 2.18 2.28 2.53
340 1.07 1.34 1.50 1.61 1.72 1.93 2.15 2.31 2.42 2.68
350 1.14 1.42 1.59 1.71 1.82 2.05 2.28 2.45 2.56 2.85
360 1.20 1.51 1.69 1.81 1.93 2.17 2.41 2.59 2.71 3.01
370 1.27 1.59 1.78 1.91 2.03 2.29 2.54 2.73 2.86 3.18
380 1.34 1.68 1.88 2.01 2.15 2.41 2.68 2.88 3.02 3.35
390 1.41 1.77 1.98 2.12 2.26 2.54 2.83 3.04 3.18 3.53
400 1.49 1.86 2.08 2.23 2.38 2.68 2.97 3.20 3.34 3.72
410 1.56 1.95 2.19 2.34 2.50 2.81 3.12 3.36 3.51 3.90

Suggested limits are based on Joulage Limit rules used at Halo Mill: Proving Grounds, and is the equivalent of 500fps, using 0.20g BB resulting in an upper limit of 2.32j.

Velocity BB Weight (Grams)
FPS 0.20 0.25 0.28 0.30 0.32 0.36 0.40 0.43 0.45 0.50
250 0.58 0.73 0.81 0.87 0.93 1.05 1.16 1.25 1.31 1.45
260 0.63 0.79 0.88 0.94 1.00 1.13 1.26 1.35 1.41 1.57
270 0.68 0.85 0.95 1.02 1.08 1.22 1.35 1.46 1.52 1.69
280 0.73 0.91 1.02 1.09 1.17 1.31 1.46 1.57 1.64 1.82
290 0.78 0.98 1.09 1.17 1.25 1.41 1.56 1.68 1.76 1.95
300 0.84 1.05 1.17 1.25 1.34 1.51 1.67 1.80 1.88 2.09
310 0.89 1.12 1.25 1.34 1.43 1.61 1.79 1.92 2.01 2.23
320 0.95 1.19 1.33 1.43 1.52 1.71 1.90 2.05 2.14 2.38
330 1.01 1.26 1.42 1.52 1.62 1.82 2.02 2.18 2.28 2.53
340 1.07 1.34 1.50 1.61 1.72 1.93 2.15 2.31 2.42 2.68
350 1.14 1.42 1.59 1.71 1.82 2.05 2.28 2.45 2.56 2.85
360 1.20 1.51 1.69 1.81 1.93 2.17 2.41 2.59 2.71 3.01
370 1.27 1.59 1.78 1.91 2.03 2.29 2.54 2.73 2.86 3.18
380 1.34 1.68 1.88 2.01 2.15 2.41 2.68 2.88 3.02 3.35
390 1.41 1.77 1.98 2.12 2.26 2.54 2.83 3.04 3.18 3.53
400 1.49 1.86 2.08 2.23 2.38 2.68 2.97 3.20 3.34 3.72
410 1.56 1.95 2.19 2.34 2.50 2.81 3.12 3.36 3.51 3.90
420 1.64 2.05 2.29 2.46 2.62 2.95 3.28 3.52 3.69 4.10
430 1.72 2.15 2.40 2.58 2.75 3.09 3.44 3.69 3.86 4.29
440 1.80 2.25 2.52 2.70 2.88 3.24 3.60 3.87 4.05 4.50
450 1.88 2.35 2.63 2.82 3.01 3.39 3.76 4.04 4.23 4.70
460 1.97 2.46 2.75 2.95 3.15 3.54 3.93 4.23 4.42 4.91
470 2.05 2.57 2.87 3.08 3.28 3.69 4.10 4.41 4.62 5.13
480 2.14 2.68 3.00 3.21 3.42 3.85 4.28 4.60 4.82 5.35
490 2.23 2.79 3.12 3.35 3.57 4.02 4.46 4.80 5.02 5.58
500 2.32 2.90 3.25 3.48 3.72 4.18 4.65 4.99 5.23 5.81
510 2.42 3.02 3.38 3.62 3.87 4.35 4.83 5.20 5.44 6.04