Spring MPX to AEG Conversion

Hey, doods. So you have acquired that goofy ahh MPX springer and you're wishing it could keep up with any of the performance AEGs out there without forking over 450 to the airsoft industry and then 30 more for magazines. Well well well I have the solution for YOU. Listed below are some crude steps in how to make it possible with 80% tutorial here and 20% of your know-how with common hand tools. Let's get started.

Things that will be accomplished:

Your very own custom MPX at a fraction of the cost
MP5 magazine utilization (TM standard fit)
V2 gearbox compatibility
M4 hop chamber
Buffer tube stock for battery fitment

Things you need:

Rotary tool with plastic/metal cutting end and sanding drum
Small need nose pliers, flush cuts
Sandpaper
Measuring device, calipers preferred
Drill with assorted drill bits
3D printer (I hope you have this)
V2 gearbox with M4 internals
M4 hop chamber and inner barrel
V2 standard motor grip
MP5 magazines
Bolts and other hardware listed above in the pictures
*M4 selector switch (TM standard)

Step 1:

Download all five files and print them with at least 30% infill at .12mm layer height. The magazine catch needs to be printed with 50% infill or higher to ensure rigidity/strength.

Step 2:

Tear your spring MPX apart and begin to remove material in areas highlighted with red. It is nearly everything on the inside, can't really mess this up. Remove the molded grip via outline on the body however do not remove the backstrap piece. If you do this there is a chance to make a huge hole. Remove the 36mm strip piece above the trigger as shown in the picture, this help the gearbox rest flush in the shell while providing alignment to the barrel. Test fit the gearbox between the two shells and keep removing material until it closes easily. There WILL be a small gap on the side of the gear box with the selector plate, this is to be expected.

Also find in the pictures where to make additional hole for the hop chamber adjustment. Currently this hole works with standard TM hop chambers, have not tested rotary.

Step 3:

Place in your gearbox shell inside one of the MPX halves and mark holes for the body pins. Note, the pin holes do not line up with the molded 'pins' on the body. The easy way to do this step is to combine your outer barrel, hop chamber adapter and hop unit into the shell as well then press the gearbox into place. Mark where to drill holes, remove gearbox, then make holes for the 3mm screw and M4 body pin.

Step 4:

Make a small cutaway at the rear of the MPX shell at the bottom of the picatinny section. This is for the rear wiring. Front wiring is also possible by removing more material from the shell and tracing the wire to the front. This can be done if wished to keep the original stock however you will need a mock peq unit for the battery.

Step 5:

Install M4 selector switch into left side MPX shell. Fitment will be loose yet does not affect operation.

Step 6:

Rear wiring will need to be spliced to allow wires to pass thru opening in the stock, Dean connector too big for hole. Can be done by using 3mm spade connectors, same type that connects to motor tabs.

Step 7:

Place components together. Magazine well can be placed and secured via 2 screws on the outside of the body. At first the fitment may be tight yet it will conform once removing and inserting the magazine a few times. The mag catch is straight forward. Slip it through and attach with existing mag release button. Secure the clam shells, add the mock charging handle and you are done.

Step 8:

Yeah, I know, this tutorial is awful. I do not write documentation on hardly anything and I am more of a "monkey see monkey do" type of learner. If this is too hard to follow or to see where pieces go I may need to make a video. At this point you should have it done and knocking out some fine adjustments.

Enjoy your bootleg MPX AEG! ... I hope.