Specna Arms Complete Reinforced Gearbox V2 with Electronic Contacts - Rear Wired

Specna Arms
Code: SPE-08-023726
  • Complete gearbox
  • M110 Spring installed
  • Electronic trigger

For those who like to build their own AEG, and for those with a dead gearbox who aren't up for the fiddly and often frustrating process of repairing it and putting it all back together, this one is for you! This Specna Arms Complete reinforced Gearbox is a version 2 pattern gearbox designed for use in M4/AR15 AEG replicas.

Full description


Specna Arms' Reinforced Gearbox with Electronic contacts is intended for use in an M4/AR15 AEG replicas as a complete replacement for your original gearbox, or as part of a scratch-built AEG project. This particular gearbox is Specna's highest spec'd complete gearbox, sporting the Enter and Convert quick change spring system, an Aluminium nozzle, electronic trigger contacts and 8mm slide bearings, guaranteeing smooth and snappy performance.

The gearbox shell is finished in a light blue colour, which is a nice touch giving the gearbox a custom look, despite the fact that most of it will not be visible when inside its future host receiver! The shell also features radiused cylinder corners, addressing one of the few weaknesses present in the Version 2 gearbox design, and ensuring that this gearbox is up to the strain of using higher strength springs. The gearbox also comes with quite the cool enhancement which is actually visible on the outside! The flat-faced speed trigger, which is finished in blue, drops a sly hint to your enemy that all may not be as it seems with your M4!

The internal parts present in the gearbox are as follows: Reinforced 18:1 ratio steel gears, polymer piston with steel final tooth, air seal piston head, dampened cylinder head, aluminium type 0 cylinder, aluminium nozzle and steel spring guide. With an internal spec like that, you can be sure this gearbox is capable of smooth, reliable function and impressive rate of fire and trigger response to boot! This gearbox is set up for rear wired AEGs and is ideally suited to a setup with space in the stock or buffer tube for a battery.

The use of electronic trigger contacts both improves your trigger response and helps the electrical current provided to the motor to be used more efficiently. The best thing about it? You don't have to do any installation! No soldering, no messing, no trouble shooting, just drop the gearbox into your receiver with your chosen motor and you're ready to go with one of the most well equipped complete gearboxes on the market, and definitely the best in this price range!


  • Reinforced gearbox shell
  • Radiused cylinder window corners
  • Quick change spring (Enter and Convert system)
  • Aluminium nozzle
  • 8mm Slide bearings ensure smooth running
  • 18:1 Steel gearset 
  • Rear wired gearbox
  • Flat-faced trigger finished in blue
  • Electronic trigger contacts

Package Includes

  • Specna Arms Complete Reinforced Gearbox V2 with Electronic Contacts - Rear Wired

Special instructions

The spring installed in this gearbox is rated at 110m/s and should give around 400FPS when installed in an AEG with good air seal. Bear in mind that this is above UK legal skirmishing velocities, and unless you are intending to lock this gearbox to semi-automatic it will need a velocity downgrade in the form of a weaker spring before it is skirmish ready.



Internal Part Type
Complete Gearbox, Gearbox,

Weight and Dimension

Weight KG Icon
Weight (KG)
Approx. 0.516kg


Colour Wheel Greyscale
Item Colour
Light Blue
Construction Icon
Alloy shell with steel gears, various aluminium and polymer internal components
Internal Part Construction
Polymer, Alloy, Steel, Aluminium, Rubber,

Part Specific

Part for Power Source Type
Weapon Platform
  • AR Platform
  • M4 / AR15 / M16
  • 416 Series
  • Long Gun
  • Assault Rifle
Package Includes
Complete Gearbox

Electric Part Specific

Gearbox Icon
Gearbox Version
V2 Gearbox
Gearbox Version Compatibility Variant
Version 2

Size guide

Parts Fitting

Upgrades and Downgrades should only be undertaken by experienced players, or Airsoft Technicians. Please note, changing any internal parts of a weapon voids its warranty unless done in-house by our staff. 

Please ensure that when fitting parts the part purchased is the correct part, as once a part has been fitted we cannot accept return.

We do know that players love to tinker, so we're here to give you help should you require it, and if needed you can get in touch with our workshop for more help!

Unique Parts

Please note that some parts may be unique to a specific brand of weapon. For example: Parts for an ASG M4A1 may not fit an ICS M4A1.

Parts from the same brand typically have a high chance of fitting, though be warned, some replicas use unique parts, so please ensure the part will fit before you attempt to fit it.

If you require help with fitting any parts feel free to get in touch with us via our Contact Us Page.

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