This is Part II of my Airsoft MOSFET Custom Installation Guide for an M4 AEG.  In this particular case, I'm working on an Elite Force HK416 CQB AEG, but this guide is good for pretty much any standard M4 AEG that uses a buffer tube.

I left off my MOSFET Custom Installation Guide - Part I once I had pretty much covered the process of rewiring for the motor & grip.  So now, we will take more of a look at the back-end of the gun, which is where things really get fun.

Check out Part II after the jump...

Ah yes.  We will be revisiting my beloved Elite Force HK416 CQB by VFC this week with a guide on how to install a MOSFET unit inside your rear-wired M4 Airsoft AEG.   
She has been in pieces for far too long now (for the better part of a year, I'm ashamed to admit).  It all stemmed from a stripped piston last year during the Association of Competitive Airsoft Expo that I participated in with a few fellow members from my Airsoft team, Level X. 
Since I had to open up the gearbox anyway, something I had refrained from doing unnecessarily since tuning my HK416 a year or more prior to that, I decided to take a thorough assessment of the wear & tear on the internal parts of the gearbox to see if anything else needed repair or replacement.  Eventually, when I got to the trigger switch, or wire harness as some call it, I found that one of my copper contact plates had burnt up pretty good over time, undoubtedly due to the fact that I had been running 11.1V Li-Po battery packs exclusively in that gun for over a year and had used it quite often (the Elite Force HK416 CQB makes for a phenomenal workhorse primary).
While I don't pretend to be a true expert here, I'm of the opinion that the best way to prevent this wear and tear on the trigger contacts while still being able to run Li-Po battery packs is to install a MOSFET computer unit in your AEG.  So since this was, and still is, my favorite of the M4 variants in my little collection, I felt it deserved a MOSFET and was worth the effort to install one.  I will preface the rest of this blog by saying that this installation process has turned into a much more complicated project than I had originally anticipated, but I plan to see it through until I can get my HK416 back up and running because, like I said, it's worth it. 

This isn't my first rodeo with installing a MOSFET, but in the past, I've done it on guns using a full, fixed stock, like my Marui M14 or Classic Army SR25.  When I initially made the decision to take on this project, I failed to take the HK416's buffer tube into account, since this Airsoft AEG is wired to the back.  Oh well.  Adapt and overcome.  Otherwise you will lose.  Since I have an allergy to losing, I wasn't about to give up.  

So, initially, I wrote this blog about my MOSFET-in-the-buffer-tube mod.  Keep in mind that it only covers what I did to fit the MOSFET in the buffer tube and still allow for you to be able to connect all the wires and secure the buffer tube to the back of the receiver.