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In early May I had put in a preorder for one of AWS Airsoft's Stealth Drop-in mosfets. Soon after I received an email about the ETA for the next Stealth parts shipment, and also that any existing preorders could upgrade to the new Raptor mosfet model for the difference in price. I was intrigued that the Raptor claimed to have almost all the abilities of the other mosfets being offered, so I upgraded my order and received it a few weeks later. The Raptor would be going in my SR-10, which turned out to be a bit of an adventure due to KWA's "unique" V2 gearbox. Luckily I had an excellent gunsmith with me who was able to sort through it all.


The technical info and features of the Stealth can be found on the AWS Raptor page.



The Raptor mosfet package includes the mosfet itself (in 2 pieces), some extra shrink rap, a matching connector, new fire selector plate spring, and the instruction packet with programming instructions.




Everything seemed properly assembled, solders on the board and the plugs were done well. The first thing to do was modify the fire selector plate.

(After on top, before on bottom) (Shown with supplied extended cutoff lever spring)



With that done, the only other standard modification that needs to be done is to straighten out the trigger torsion spring so that it does not damage the mosfet circuit board. We dropped the mosfet in and it sat in place perfectly, maybe a millimeter of give either way. When we started to put it back together, we noticed that the trigger and trigger safety control was coming into contact with the wiring coming out of the mosfet. To be safe we pressed the wires down a bit so that no contact was made.





With that fixed we put the gearbox back together, but a few more issues came up. You can kind of see it two pictures up and in the picture below but part of the circuit board enters the hole where the trigger post would go, and it put tension on the mosfet board itself.



There was no real way to push the mosfet farther into the corner, so our logical solution was "Drill baby, drill". So we drilled a little off the board. And then a little more. And then too much. Luckily we did not cut the traces on the board itself, but according to Frank from AWS we came super close. Be aware if you have to do this on your own.



The next issue came about from the wiring. I'm not sure what other makers' V2 gearboxes have in them, but inside KWA has little posts around the back of the box to keep the battery wires in place. With the addition of the trigger wires going back to the stock these posts were pushing into the battery wire, preventing the box from closing. So off they went, dremeled back to heaven.




With that the gearbox finally came together. The final two issues I was not able to take photos of but I will explain as best I can.


Final Issues


After putting the gearbox together we tested it to see if everything was working right. Setting it on semi resulted in a .5 second 6-burst fire. The same happened on auto. We were originally worried that we had actually cut something important out of the mosfet when we were drilling earlier. After talking with Frank it turned out the cutoff lever was making insufficient contact with the cutoff switch on the board. The chip did not know when the end of the firing cycle was, so this was basically its way of saying "somethings wrong". A touch of plastic glue was added to the end of the lever which totally fixed this problem.


Our last issue was with the upper receiver. Once again I do not know if this is just a KWA issue, but the ring on the upper receiver that you put the bolt through when you put it together with the lower receiver was coming into contact with the selector plate. A date with the dremel fixed it up quick.

Final Thoughts


And after all that, it works perfectly! As I mentioned earlier this mosfet does include a programming mode similar to their other mosfets which is what I was looking forward to. Holding the trigger down while plugging the battery in will give you 16 different options.

Some of the programming options include:

2-4 LiPo cell monitoring for you 14.8v monsters

RoF reduction (Max/20/15/10rps)

Active braking on/off


and the normal range of fire commands:




Safe/semi/semi pre-cock


I did notice that the instruction manual states that while in programming mode each command is followed by a buzz, but this was not the case. I asked Frank about it and he confirmed that there is no buzz or vibration to let you know a command has been input. It's not really a problem, just make sure you time you trigger clicks appropriately when programming.

The trigger itself is noticeably easier to pull. The stock KWA setup was by itself easier to pull than any of my other guns, but now I would it's about a 2-3lb pull. That, coupled with the fact that with the setup of the trigger assembly a half-pull will fire the gun! I believe there is a video on his website that will attest to this, I did not have time to shoot one of my own.


This Raptor mosfet is pretty much all I expected it to be. Considering this is its first production run I have no complaints. I accept that the modifications that had to be done to it were due to the fact that not all gearboxes are the same. My gunsmith remarked that most of the issues we ran into probably were not going to pop up on a TM gearbox he had ordered his own Raptor for. At its current price of $90, it's one of the pricier mosfets out there. But what it can do, crammed into the space of your trigger assembly makes it one of the best mosfets out there in my opinion. Extra wiring and modules are a pain the butt, especially in guns with little room to spare. Since I've put this in I have not had a single issue with it, and all its features have worked perfectly as of this post. Can't wait for a V3 version to come out!

Edited by Kaoru
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