New Retro Arms Electronic trigger processing unit !

We are exited to see a new kid on the block to take on the troublesome ASCU units. Below is some information released from retro arms. We are exited to test one of these new units!

Processor unit for our gearboxes

This is a program-controlled device with motor active braking. It has six shooting modes, controls rate of fire, precocking, active braking and low battery indication. The device is fully integrated inside the RetroARMS gearbox. The gun trigger is used for programming this device, the motor vibrates as a feedback for the user. Coated with lacquer, it protects device against water.

Maximum battery: Ni-xx 8.4 – 12V, lipol 7.4 – 11.1V

Maximum AMP: 25amp

It means no more adjusting our trigger and contacts in your gun!
Unit comes with all wires and programming scheme
Here are functions of our processor

1. choice

  • 1.attribute: Semi – Full (standard shooting)
  • 2.attribute: Semi – Burst/Full (factory default)
  • 3.attribute: Semi – Semi
  • 4.attribute: Semi – Burst
  • 5.attribute: Semi – Semi (delay)
  • 6.attribute: Burst – Burst/Full (one push on the trigger gives Burst, long push give full auto)
  • 7.attribute: Semi/Burst – Burst/Full (same function like attribute 7..)

2. choice

  • Burst time – Reduction (-12% burst time)

3. choice

  • Burst time – Increase (+12% burst time)

4. choice

  • Motor speed – Reduction (-5% speed)

5. choice

  • Motor speed – Increase (+5%speed)

6. choice

  • 1.attribute: Short
  • 2.attribute: Medium
  • 3.attribute: long
7. choice
  • 1.attribute: OFF
  • 2.attribute: ON

8. choice

  • 1.attribute: OFF
  • 2.attribute: ON

9. choice
Active brake

  • 1.attribute: Off
  • 2.attribute: Low intensity
  • 3.attribute: Medium intensity
  • 4.attribute: High intensity

10. choice
Low battery indication

  • 1.attribute: Off
  • 2.attribute: 2S li-pol
  • 3.attribute: 3S li-pol
  • 4.attribute: 3S li-fe
  • 5.attribute: 3S li-on

11. choice



  • 1.attribute: same as normal AEG (without Processor unit)
  • 2.attribute: on AUTO press trigger short to shoot burst (3 shots), if trigger is hold down longer it goes to auto fire (factory default). SEMI fire unchanged.
  • 3.attribute: it fires single shot with selector on AUTO. SEMI fire unchanged.
  • 4.attribute: it fires burst (3 shots) with selector on AUTO. SEMI fire unchanged.
  • 5.attribute: it fires only single shot with forced time delay for the next shot (programmable delay- 6.choice). Motor vibrates when it is ready to fire. The first 3 shots on SEMI are without delay (skipped after 2 min inactivity).
  • 6.attribute: it fires burst (3 shots) on SEMI. On AUTO short trigger press fires burst. If trigger is hold down longer the gun will go to auto fire. The first 3 shots on SEMI are single shots (skipped after 2 min inactivity).
  • 7.attribute: on SEMI short trigger press fires single shot, if trigger is hold down longer the gun will shoot burst (3 shots). On AUTO short trigger press fires burst, if trigger is hold down longer the gun will go to auto fire. The first 3 shots on SEMI are single shots (skipped after 2 min inactivity).

BURST TIME – Each trigger press will shorten/lengthen burst time about 12%. You can refine burst cycle or increase/decrease the number of bullets fired in burst. To change the number of shots about 1 press trigger 8x to10x. (Factory setting is 3 shots, range 1 – 10 shots)

MOTOR SPEED – Each trigger press will slow down/speed up motor about 5%. It is useful for too high gun rate of fire (RoF). (Factory default is 100%) WARNING – Do not slow down motor speed too low, it could destroy processor unit. Recommended minimum RoF is 10 bb/s.

DELAY – The time, in which it is not possible to shoot again in FIRE MODE 5. Default delay is Medium, you can choose shorter or longer period of time. Motor vibrates shortly after pass time delay. It is notification to shoot again. 6 Detailed programming scheme 2/2

PRE-COCKING – If is this function active, the piston is partly compressed after fire on semi. There isn’t almost any delay between trigger press and shot. If you hold the trigger after firing at least 3 seconds, gun shots again, but this time with a piston in a released position – use it before storing gun. Pre-cocking works only with functional active brake (9. choice). (Factory default = OFF)

FAST SHOT – It works only with MOTOR SPEED – Reduction (4.choice). The first shot is always at 100% RoF, next shots are fired with user set lower RoF. This function is used for quick gun response. (Factory default = ON)

ACTIVE BRAKE – If is this function active, it uses the excess energy from the motor to stop it. On SEMI fire piston isn’t partially stretched, spring is fully released, parts in gearbox aren’t under strain and nozzle locks hop-up chamber in greater part (depends on RoF). The braking effect is the most powerful with high torque motor. In AUTO mode piston stops in random position due the gearbox design. But it stops much faster with active brake. You can choose 3 intensity of active braking or turn it off completely. Higher power braking is suitable for weapons with high RoF. (In the factory default option is turned on medium braking intensity)

LOW BATTERY INDICATION – it is used for only Li-xx batteries with the right number of cells. When processor unit detects low battery voltage, it will vibrate after each shot. Now replace the battery at the nearest opportunity. When the battery is depleted the gun vibrates instead of fire. The battery isn’t disconnected, device very slowly discharges it. (Factory default = OFF)

FACTORY RESET – When you enter this option, immediately press and hold the trigger until you feel long vibration -> the gun will no longer respond for anything. Disconnect and connect the battery = device is back in factory settings.



About Laurence Kay

Laurence is a keen airsoft player and has been the owner of SoCom Tactical for over 10 years. He’s played airsoft all over the country solo and as part of teams and is an expert on all things airsoft, like tactics, airsoft guns and gameplay equipment. As one of the UK’s leading airsoft suppliers and retailers, Laurence is the go-to source for airsoft knowledge.