Airsoft M4 to MCX upper receiver drop-in conversion kit.

Test receiver available now!
https://www.thingiverse.com/thing:4842807
Use the above file to see if this kit will fit your lower receiver.

In partnership with Guzshop, I have produced an easy kit to convert your airsoft M4/AR15 style RIF into a representation of a Sig MCX.
As with many people in airsoft, I want to have all the gucci gear, but don't have a gucci wallet, so I try to find cheaper alternatives to acquire the gear I want.
Since the real steel version can be used with a standard M4 lower, I thought I'd try the same in airsoft, using a Specna Arms M4 as a base. Altogether, the cost of an Ender 3 pro, the materials and the Specna Arms Edge series rifle came to less than the cost of a Sigair MCX. Obviously, it's not the same quality, but it looks close enough for me!
Once printed, the process of converting your airsoft rifle is as simple as removing your current upper receiver assembly and replacing the MCX upper on there. The outer barrel also is printed with a 14mm CCW thread on there to take your chosen muzzle device.

For UK based customers I can also offer these as a pre-printed kit.

Assembly:
You will need - 3 M5x12 bolts, superglue, donor airsoft gun, printed parts, drill and bits, tap and dies (optional).

Slot the upper rail into the upper receiver, secure with one M5 bolt through the hole provided. Drill down through the hole (be careful not to widen the hole in the upper rail) roughly one centimetre.
You can now screw the M5 all the way down (don't overtighten, you'll be threading into plastic). You may choose to use an M5 tap to create the threads.
Place the upper receiver and upper rail assembly onto the lower receiver (including the airsoft internals). Test fit the outer barrel assembly over the inner barrel. Once the fit has been tested, add superglue to the base of the outer barrel carefully - we don't want to have excess glue touching the inner barrel. Align the outer barrel using the inner barrel, and hold in place until solid.
Finally, slide the handguard on, and use two M5 bolts through the base to secure it using the same process as before.

Please drop me a message, I'll be happy to video chat anyone to talk through the build if needed!

Everything is designed to be printed on an Ender 3 sized bed.

Whilst I cannot guarantee that this kit will fit every airsoft M4 with no modifications, I can confirm that it fits a Specna Arms replica and compatible parts.

I plan on releasing longer handguards (including a virtus inspired one) and a barrel extension, so keep checking back here for updates!

All parts should be printed vertically.
I've used ESUN PLA+ on mine, using Cura to slice and an Ender 3 Pro.

Cura will state that the object is not manifold - it still prints absolutely fine.

Outer Barrel settings:
210° nozzle, 60° bed.
0.12 layer height.
50mm/s.
6 outer walls.
50% infill.
Standard supports (trees works, but wastes a lot more material as well as being tougher to remove).

For the rail, upper receiver and handguard I used the settings above, but printed at 0.2mm layer height to reduce print time. Printing at 0.12mm would increase strength and improve the finish, but would increase the print time too.