"Gearbox internal review:
Gearbox shell - 3.5/5
The gearbox shell itself honestly doesn't seem that strong; I also own the Matrix QD gearbox, and it is a LOT stronger. Also, in order to fit my SHS 13:1 gear set, I had to shave off some parts with a Dremel, so if you plan on replacing the gears, I hope you have a Dremel. Definitely not the shell for a DMR set up, but I think it'll stand up to anything lower than an M140 or lower perfectly fine.
Air seal nozzle - 5/5
The stock air seal nozzle is FANTASTIC!!! It's made of CNC aluminum, it's strong, it's lightweight, and provides a VERY nice air seal. Definitely the most impressive stock air nozzle I've ever seen.
Cylinder head - 4/5
Very good stock cylinder head. It's made out of polycarbonate, but the stem is made out of a nice aluminum. It provides a nice air seal with the stock cylinder; add some Teflon tape and you won't even need to buy another cylinder head. It comes with a nice, thick SorboPad pre-installed; nice touch, though it doesn't completely correct the AoE.
Cylinder - 4.5/5
Good cylinder. It's metal, some kind of shiny-ish silver. It's nice and smooth on the inside, so less friction between it and the piston head. It has a port meant for a standard M4 inner barrel (363mm), which doesn't really suit my 509mm inner barrel, so I switched it out. However, if it fits your inner barrel length, there is absolutely no reason to replace it.
Piston head - 4/5
It's a really nice polycarbonate piston with eight ports, but the o-ring SUCKS BUTT FLUPS. GET ANOTHER PISTON O-RING FROM HOME DEPOT FOR THE LOVE OF GLOB. Once you do, it provides a very, very good seal, no need to replace this piston head either.
Piston - 3.5/5
Standard stock piston. One steel tooth, rest of out made of polycarbonate, last tooth removed to help with AoE. It should serve you just fine, though replacing it to better suit your set up is a good idea.
Spring - works as a spring
It's a spring. It provides springy powers. I didn't chrono with it as I immediately changed the spring, sorry to disappoint. If I had to guess, it's either an M110 or M120.
Spring guide - 3.5/5
It has a metal base with smooth, metal ball bearings, which is nice, but the shaft is made of polymer. This is the same for the Matrix QD gearbox. I just don't see why they can't just make a metal one.....
Gears - 3.5/5
I'm not using these gears; as mentioned, I'm using SHS 13:1 gears. These gears seem to be an 18:1 ratio, but honestly, they don't seem too robust. But like I said, I'm won't be using them, so I can't test them. They come pre-installed with a sector chip.
Wiring - 5/5
It comes with low-res wiring, and the trigger contact is awesome! Definitely don't need to replace the wiring.
Mine came with a broken trigger. Don't know if that's APS's or UPS's fault, but it's worth mentioning.
As stated above, I had to do some Dremeling to fit my SHS 13:1 gears.
The blowback doesn't fit with my G&P upper receiver, though I wasn't expecting it to, so it's fine.
"I bought this gearbox over the summer because I was looking for replacement for my JG gearbox. I somehow managed to break off the trigger post so it rendered the entire gearbox useless. I figured this would work and since it was quick-change spring, make repairs a breeze. When I received it, I noticed it was missing the fuse and battery connector (I had a spare from my old wire harness so it worked out). I tried to fit in the JG plastic body but had no success.
After an hour of that, I then decided to test the gearbox itself by installing the motor and grip. As soon as I plugged in the battery, the gearbox fired without me pulling the trigger. I switched it to safety and the box kept cycling, requiring me to unplug the battery. I opened the gearbox and found out the wire harness was to blame for that issue. So I changed out the wire harness and problem solved. Luckily I had a metal receiver from an AGM at the time and this gearbox fit like a charm inside of that (I had to disable the blowback feature and remove the bolt catch). I ran a test prior to skirmish and it worked, but on skirmish day the gearbox completely locked up on me, so it was failure. Ever since that day, I can't get the gearbox to complete a cycle on semi-fire without locking up and full auto is faulty as well.
Gearbox fires like a champ when it works.
Quick-change spring makes repairs a breeze.
Gearbox is beefy; shell is thicker than most other brands.
Trigger harness caused gearbox to cycle without me pulling trigger.
You will need a metal body that is compatible with this gearbox (I heard a rumor that G&G's GR16 blowback as well as Combat Machine blowback series are capable of housing this gearbox with the blowback enabled, but I don't know if it's true)
"quality gear box
workmanship is up there with the best ive seen.
shimmed really smooth.
installed into matrix m4 with 363mm 6.04 brass barrel
blowback plate not used, removed blowback spring from top of gear box
very nice fit.
swapped out oem spring for matrix m130
running 11.1v 1300MHA 15C BATTERY with matrix high torque motor.
puts .23gr bb through one side of 5 gallon bucket at 50ft, sometimes both side.
its such a quality gear box that i purchased the APS ASR 110 m4 today as it also has a hybrid gear box only difference is 7mm bearings instead of 8mm.