ASCU V2 fitted to an APS ASR-110

I was up until 1am last night working on installing the ASCU V2 to the APS ASR-110 (2012 version). I should say before I get started that the 2012 version definitely DOES NOT have a MOSFET fitted despite what the retailers will tell you. All the other specs seem to be accurate. The ASR-110 uses one of the new hybrid gearboxes which seems to be pretty good, I found one structural weakness related to the E B but to be honest I could take or leave EBB... The only EBB systems that have impressed me have been the ARES G36 and TM recoil rifles...

APS ASR in Black (also comes in DE)

Before installing the MOSFET I had a quick look through the instructions and checked the gearbox. I found (the hard way) that my selector plate was metal. I have never seen a metal selector plate in a stock AEG and I am sure this is a QC error from APS. Anyway, a friend sourced me a new plastic selector plate that I sanded down to size. I would strongly advise NOT cutting it with snips like the manual suggests... This is purely because the cheap rigid selector plates will shatter and you'll have cost yourself £10 or so...

So, to remove the gearbox I had to separate the upper and lower ,then remove two body pins. The one next to the trigger and at the rear. The stock tube has a large screw inside it which unscrews and releases the rear of the gear box. I then unscrewed the motor plate, removed the motor and unscrewed the pistol grip. Finally all I had to do was remove the magazine catch. Once this was done the gearbox still wouldn't lift. It appears as is APS have installed a functional bolt catch that stops the gearbox from lifting out. All you need to do it get a pin pin punch and knock the pin out and pull the bolt catch out.

Once I had pulled the gearbox out, I removed the main spring to reduce the tension in the gearbox. Now I had a very typical version 2 gearbox sat in front of me. I proceeded by unscrewing the spring loaded bolt catch that is attached to the gearbox - it covers one of the gearbox screws. I would like to mention tone careful with this part as the spring can launch out. It happened to me but thankfully my mechanics bowl "caught" it. I undid all the gearbox screws then used a thin screw driver to open the gearbox. Force of habit for me is to open the gearbox is such a way I could use the screw driver to hold down the anti-reversal latch (ARL).

At this point I would like to take the time to express my hate for the ARL. It's a horrible component in the gearbox and responses for many rage quits in my products... In fact... The ARL was responsible for the decision to sell my last G36.

Once I opened the gearbox I removed all the gears making sure to note on a piece of paper how many shims were in each gear both at the top and bottom. I did later re-shim the gearbox but its somewhat irrelevant as the gearbox was well shimmed and arguably I wasted my time trying to improve it. I removed the trigger and piston components. I then unscrewed the old selector plate and installed the new trigger sensor unit. This is where the first modification came in. The screw that holds the trigger mech in place is too long for the sensor unit. It protrudes out and would later interfere with the selector plate. I ended up cutting 2mm off with snips which worked.

I then ran the data cable from the sensor unit out the gearbox. This is the easiest bit to get wrong. If you don't fit the data cable correctly then the body pin will cut the data cable either disabling the ASCU or messing up your full auto capabilities. I fitted the motor cables to length so that when the pistol grip was fitted, it would fit perfectly with no slack. This required some fitted of the motor and pistol grip to check length. I ended up using a weak adhesive to glue down the cables just to make sure. We're talking about a threadlock style adhesive applied with the tip of a tooth pick. You want to be careful as glue in the gearbox can ruin your kit!

Once the wires were laid, the gearbox was reassembled and the gears were held in place using rare earth magnets. I'd recommend using magnets, it will make your life a lot easier! The gearbox was fitted back into the body and the body pins were fitted. I'd strongly recommend at this point using an allen key to clear the holes just in case the cables are in the way. This will help prevent cutting the wires! The stock tube was replaced with the nut and screw and it was tightened. I spent a lot of time on this making sure the power wires weren't cut from the rotation of the nut.

That was me pretty much done! The entire process took about an hour. I am no experienced gearbox tech but I am sure this could be done in half the time. A lot of care needs to be taken with the data cables. Mess that part up and you have ruined your MOSFET and potentially more!

I did in fact manage to snip one of the data cables and now my gearbox is locked to semi-auto which is a pain. A new data cable has arrived but due to studies, I haven't had the time to work on my gearbox or my blog :( I would strongly recommend a MOSFET trigger system, the trigger response of my gun has been hugely improved and it protects my gun against my insistent use of LiPos.

My next project is looking to be a TM next gen. HK416D which be tricked out with a spectre drop in FET from BTC, a Noveske outter barrel, a flare function tracer and a TK twist barrel.