Airsoft Systems ASCU Fire Control System for Ver 2 AEG Gearbox - Gen 4

Airsoft Systems42081
3.9 stars, based on 11 reviews


ID: 42081 (Burst-ASCU-V2G4)
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11 Customer Reviews

by Morgan S. on 11/01/2015
"My personal experience with this product was rather poor. The connectors between the two control boards broke quite soon, so I'm afraid I can't recommend this product. It's extremely poorly designed, for the price, there are many better options.

Pros of any simple mosfet system:
-Protects your trigger contacts and electrical system

Pros over simple mosfet systems:
-Marginally reduces trigger pull force
-Ensures a full piston cycle (improves trigger response and mechanical longevity)
-Three round burst if you want it
-No soldering required

-EXTREMELY fragile connectors are prone to breaking at the slightest touch
-Uses extremely stiff wire instead of wet noodle wire, making the install a pain
-Poor electrical design, many users say it burns itself out extremely soon

Really, the only core advantage of this mosfet over cheaper and simpler systems is that it gives you full piston cycles. The reduction in trigger pull isn't very perceptible, three round burst is really just a gimmick, and any good airsoft tech should be comfortable soldering.

Furthermore, the warranty service is seemingly nonexistent, as I have emailed them twice about my problems to no avail.

So, I'd advise you to stay away from this product. If you want a mosfet that gives you full piston cycles, I'd recommend one of the mosfets made by Black Talon (not offered on They have superior construction, better warranty, and are simply a better product for almost the same price. They might 10 or 20 dollars more than the ASCU, but it's well worth it.

If full piston cycle isn't important to you, then learn to solder and make your own darn mosfet. It quite literally costs 10 dollars to make one.

The point is, stay away from this POS.
by Chas G. on 09/12/2015
"I just finished installing the ASCU-2 Gen 4 into my heavily modified, Lonex based gun. The install was completely smooth and trouble free. Others here have said that they had to modify the unit to get it to fit into the shell, I did not experience any of that at all. The unit slide right into my Lonex gearbox perfectly! Everything fit like it was made to fit into my gearbox shell. The only modification I made was changing out the small Tamiya battery connector to a Deans connector. Super simple for me.

I have a Lonex A1 motor in this gun and figured that would be considered an up graded motor so I left the anti-reversal latch out of my built and it worked perfectly.

I also had a SPEED trigger already in this gun and so with some minor tuning of the trigger throw I had it set to have an incredibility fast and very slight trigger pull to fire a shot. This system was made to take advantage of the SPEED triggers.

I simply followed all the instructions in the well thought out, English manual that comes with color pictures as well. So often in airsoft we buy stuff that has either useless or non-existent instructions. This fire control unit kit has a very well written (actually a couple typos, but who's counting) and easy to understand manual! Such a relief as there are a couple of things that if you install this wrong you can destroy your unit.

After it was in and the gun put back together I test fired it quite a bit and it worked flawlessly! In a week I will be using this gun at a large MILSIM event and hope to see the full nature of this system in action.

-Easy to install
-Instantaneous trigger response!
-Well thought out system
-3 round burst FTW!
-Detailed manual

-Needs to have an up-rated motor to work properly and as designed
-Delay between trigger pulls in semi and 3rd burst mode (probably a designed in feature, but I wish it had less delay between pulls. I am nit-picking here.)
by Linda S. on 06/15/2014
"Love this unit! It takes some modification to fit but it works fantastic. At first mine would only shoot half a shot then beep twice. I had new gears shimmed so well that they rotated freely, an M170 Devil Jet motor, and installed the unit correctly and had a brand new FLAME 11.1v Lipo. I contacted ASCU and apparently this is a known issue. All you need to do is cut the notches off the black piece on top of the cutoff sensor unit (it is shaped like an L). The notches push the top and bottom portions of the unit together too tightly and cause the unit to "misread" information gained from the cut off sensor. So once you flatten out that piece, it should work.

-Easy install (modifications can be done with a file and are simple)
-Very good trigger response
-Makes your AEG sound like a PTW
-Protects your battery, motor, and internal components
-Hair trigger mods are easier
-3rd burst
-Semi Auto only for DMRs
-Limits how fast you can shoot on SEMI so you do not over cycle
-Good wiring, and plenty long
-Durable motor contacts
-No soldering
-No anti-reversal latch means much smoother cycles!

-$100 for basic functions
-Very large, which is why the modifications are needed
-Wires are big (I had to modify my buffer tube and drill a larger hole)
-Need to shim your gears well, have a strong battery, have a monster of a motor, and have a good AOE to use this thing effectively and safely

Great internal upgrade. Best I've ever installed. 5 stars.
Airsoft Systems ASCU Fire Control System for Ver 2 AEG Gearbox - Gen 4
Airsoft Systems ASCU Fire Control System for Ver 2 AEG Gearbox - Gen 4


  • Ultra fast trigger response
  • Optional Bolt-Stop simulation
  • New MosFet transistors with 16 times less resistance, resulting in to faster cycle, better active brake, more shots per battery charge and less heat
  • Simple drop-in installation
  • No soldering required
  • Improves gearbox reliability
  • Updated software with easier programming (accidental hop-up program activation is impossible).
  • Improved selector plate
  • Fits all standard and reinforced version 2 gearboxes
  • Better short-circuit protection
  • 3 year world wide warranty offered from Airsoft Systems
  • Compatible with LiPo, LiFe, NiMH, and NiCd batteries from 7.2V to 12V

Package includes: FCU, Selector plate, Cut-off lever
Compatibility: For most standard Version 2 AEG Gearbox

Manufacturer: Airsoft Systems

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