CNC Machined Halo weapons. Pure UNSC Bada$$ery. Airsoft builds :D


More Pictures on page 4.

Current Progress:

View media item 2549
I'm back!

Alright, I wanted to save this until I officially go the green light for this project.

Roughly six months ago, I started working on building an assembly in Solidworks of an M2 .50 Cal machinegun as a couple of friends and I wanted to turn out some airsoft .50's and that'd be freakin' sweet. Right?!
Well, I finished that in a matter of days. Here's the final design:


And we've started to machine parts out out of plate aluminum. Here's one of the receiver bodies (we're making 3 of these in total):


Over the past couple of months, I have been working on building CAD assemblies of several UNSC weapons in Solidworks. I've started on the Halo 4 Battle Rifle and Halo 4 Assault Rifle which I'll attach pics of in a sec.

Basically, the intent is to design the external shape of the guns, and then start creating cavities on the insides for electric airsoft components such as the gearbox, motor, etc. as well as to make the magazines function as they should in their bullpup form. They will also have functioning charging handles and whatnot. The parts will then be machined from aluminum and assembled into functioning airsoft guns. The first and only ones of their kind in the world.

So while the .50 was being machined, I started working on the BR and AR designs.

The BR is made up of a bunch of different parts at the moment, and more will be added as i start adding the airsoft guts.
BR full.png
BR magazine.png
BR sight.png
BR rail.png
BR buttplate.png
BR body.png

Not fully done with that guy yet. And the grip is kind of a bastard so I took a break from that for a while and started on the AR. This one isn't as flushed out as much as the BR yet.
AR full assem.png
AR cheak rest.png
AR handguard.png
AR Top.png
AR body.png

But I'm definitely looking forward to getting these made.

Now, here's the best part of it all.
My buddy and I were also talking about making the sniper rifle from Halo 3. However, we were going to throw a twist on it and make it a gas blowback rifle. If you don't know what gas blowback means, it's basically where the airsoft gun functions exactly like a real steel rifle, but only fires airsoft bbs from a magazine. (still confused? this oughtta help:

He didn't have time to work on the SR, so I offered to take it over this spring. At my college, there is a course that I can take which is an independent design course for seniors. I pitched the project to one of my professors, and I received permission to design and machine this piece of awesomeness!

And the best part is that I'll be receiving credit for this project. Woo hoo! Can't get any better than that.

I'll keep this up to date and hopefully have weekly postings once the new semester starts. I'll be starting on this over the winter break as well so I'll post updates from that.

Below is the project description if you want to get a better idea on how the gas system works on a gbb rifle as well as some design intentions. (Oh yeah, and I'm going to try to make a working scope display as well. Wouldn't be a sniper without a scope right? haha)

The project that our group would work on is to build a green gas powered airsoft replica from the Halo 3 video game. The intent is to use an object file taken from the videogame and use it as a reference to build a scale model of the SRS99D-S2 AM from Halo 3 from assemblies constructed using a CAD package.

Internal gas-powered internal components will also be measured and modeled in the CAD package. Cavities and mounting points will be cut and finite element methods applied to the mounts to ensure structural integrity under shear and impact loading. The parts will then be machined from aluminum and the components installed and tested to determine functionality. Alignment is critical for components as mis-alignment will keep the replica from firing or cause the gas to not be directed into the inlet in the piston which will prevent proper cycling of the bolt.
WE Tech M4 gas piston assembly. Location 1 shows the inlet gas port. Point 2 shows the feed pin which strips bb’s from the magazine and feeds them into the hop-up unit.
The complete bolt carrier group with the piston installed.

hop up.png
Hop-up assembly showing the feed ramp, inlet area, and alignment ports.
trigger box.png
When the trigger is pulled, the hammer (Point 1) in the following figure, strikes a carriage assembly (Point 2) which presses a pin connected to the gas release valve on the magazine releasing a short burst of green gas or propane.

m4 magazine.png
Standard M4 gas magazine. Point 1 is the pin connected to the gas release valve. Point 2 shows where the gas escapes into the piston. Point 3 is the keeper for the bb’s which will be fed into the hop-up unit.

Aside from designing the replica to hold the manufactured/purchased parts in proper alignment, custom designing will be necessary to make all parts cooperate in the new body. An extended pin will need to be designed and placed in-between the trigger box and airsoft magazine so that the gas is released with every trigger pull. The replica magazine will need to be designed to lock into the body when inserted. This will be done with a spring-loaded retention pin connected to the body. When the magazine is inserted, the pin will then sit in a well in the magazine. A bolt-return system will need to be designed to take the impact force of the bolt carrier group and return it into battery without damaging the replica or the internal components. In addition, the bipod legs will be functional, and the charging handle will operate the bolt and reciprocate with the bolt carrier group after each trigger pull.
The projected market for the airsoft SRS99D-S2 AM would be decently large. As an industry on its own, Airsoft has grown rapidly as a sport around the world. With new developments in safety and industry standards, as well as licensing with firearms manufacturers such as Colt, Barrett, Heckler and Koch, etc. replica airsoft arms have made the sport safer and more popular. Evike, an airsoft distributor in California manufactured a short set of replica airsoft rifles based on the Halo 1 MA5B in 2014. The replica was in high demand and retains its resale value very well. Similarly, costume play (cosplay) has grown over the past years into a dedicated hobby enjoyed by many such as the 405th Infantry Division, a group of custom costume and prop makers who share a passion of building full scale Halo replicas. These two groups, in addition to the numerous physical persons who I have shared my current project of designing other Halo airsoft replicas (see below) would create a high demand for this product (in addition to the commission requests received in years past for my work in this field). To see early prototype stages of work I’ve done in this field, see: 405th - Halo Costuming . The post has received thousands of views and much support over the past years.

The above BR85 Heavy Barrel Service Rifle and the MA5D Individual Combat Weapon System are works in progress and will be designed to use electrical components so that the SRS99D-S2 AM will remain a unique project for the MMAE 494 course.

Of important note (since I do not know the final product requirements for the course), if this project needs to be brought in, internal components will be removed so that it is non-functional in compliance with IIT policy and will only be a physical video game prop which is allowed on campus.



BR full.png

BR magazine.png

BR sight.png

BR rail.png

BR buttplate.png

BR body.png

AR full assem.png

AR cheak rest.png

AR handguard.png

AR Top.png

AR body.png




hop up.png

trigger box.png

m4 magazine.png



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You are gonna do FEA ?!......... You are My Hero!

Yeah. My professor is really big on the FEA stuff so it's a requirement. Not too worried, there's only a couple places where it'd apply anyways. But I'll be posting everything we do over the semester so I'll add it just for you man. haha


Well-Known Member
Member DIN
Its times like this wish I had access to the old college tormach mill. irony I am building a sniper tonight outta nerf blaster. No FEA but some fun in CAD to scale the scope to fit the blaster. then 3D print it .

You said you are gonna make the scope work. I did some optics classes back in school.. If you need cheap optics Edmond has some Dirt cheap plastic stuff these days....... they are acrylic so a CO2 cutter could slice them to fit the scopes area with ease.



Its times like this wish I had access to the old college tormach mill. irony I am building a sniper tonight outta nerf blaster. No FEA but some fun in CAD to scale the scope to fit the blaster. then 3D print it .

You said you are gonna make the scope work. I did some optics classes back in school.. If you need cheap optics Edmond has some Dirt cheap plastic stuff these days....... they are acrylic so a CO2 cutter could slice them to fit the scopes area with ease.


Yeah. I was thinking about putting a small camera behind a magnifier (like one of those 3x or a monocle) and then connecting that to an LCD display. I haven't really flushed the idea or parts out yet 100%. Thanks for the suggestions though. I'll keep that place in mind.


Welp, boredom and a lack of desire to work on homework early has lead me to get a head start on the rifle. Just some early stage pics of parts. The chamber, barrel, and muzzle break are finished. They were actually pretty easy, so yay!
I'm only focusing on the external stuff now. I'll start making the cavities and actual mounting methods later.



Muzzle Break
muzzle break.png

Body (Pre-receiver split). Also, this one I'm still working on. It's got a lot more detail than the rest so it'll be a bit before I finish this part.

Current assembly progress


Got some more updates. Cranked out a number of parts and added detail to the body. The parts are not 100% yet. I still need to do stuff for the carry handle and the trigger guard. Then I'll start designing it as an actual machinable assembly with mounting points, screw holes, etc. Enjoy!!

Fleshed-out body:
body 2.png




Receiver block
receiver block.png

Bipod leg
bipod leg.png


Gas tube
gas tube.png

Scope Assembly
scope assembly.png
scope assem 2.png

Current Assembly Progress
Assem 2.png
Assem 2 pic 2.png


I started working on the internals over the past couple of weeks. Finally got my hands on my buddy's WE M4 so I can start measuring the internal dimensions for modeling. So now is the beginning of the real designing for this thing.

VN style m4 magazine (this is the short mag. I will also design a full mag to see how well it fits. The idea right now is to use the VN mag since it can sit further forward. Also, since it's straight/not curved like the full mag, I might design it so that I can swap the short mags inside the SR magazine shell.
m4 mag. assem 2.png
m4 mag. assem 1.png

Modified the SR magazine to hold the VN style mag. I will eventually add a channel for the pin extension between the trigger box and the firing pin.
SR mag 1.png

SR magazine assembly
sr mag assem.png

Rough trigger box
trigger box.png

BCG housing
BCG 1.png
BCG 2.png

Here's some internal views
Internal view 1.png
Internal view 2.png

With the BCG pulled back
Internal view 3.png
internal view 4.png

So yeah. Gunna be modeling more of the parts over the coming days.


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Community Staff
Member DIN
They are not going to let you in to any cons w/ this thing!!!!!! too freaking real!! Amazing.


Thanks for the support guys! :D

I'm now officially done this semester so that means only one thing. More updates faster! Not only will I be posting updates on the SR, but I'm also going to be working on the other guns as well and posting updates on those as they come in. So more content for the viewing pleasure of your helmet visors!

Alright. Lets start off this month with a new part. I took the piston out of the m4 BCG and did my measurements and magic and modeled it up in cad.

Here's the m4 BCG that I modeled to get dimensions from:

m4 bcg.png

And here's the piston that I modeled:
piston 2.png

Here it is in the BCG assembly.

BCG assem 1.png
BCG assem 2.png

And in the full assembly.
SR assem piston.png
SR assem piston 2.png

This is one piece that I'm really happy I was finally able to model. It means that I have officially moved onto the critical alignment portion of this design.
Using that I began aligning the SR BCG and magazine. So I have updated some of the parts.

I updated the BCG for one. Since the trigger box will be in a completely different spot than how it is set up in the m4, I removed the cutout from the center of the SR BCG.
SR BCG 1.png
SR BCG 2.png

I am also in the process of figuring out the return system for the BCG. My thoughts right now are to screw an extended cylinder to the end of the SR BCG which will model the m4 BCG. This way, I can mount another block that will house the return spring for the BCG. Since the overall travel of this bolt will be roughly 4 inches, I will make the extension 4 inches. Now, I'm doing this so that 1. It will act as a guide and 2. because I do not believe that I would be able to mount the return spring any better way. I contemplated about having a rod with a spring on it run down the center of the BCG but I do not believe that would work as well as we need. It also did not work when my friend in MI attempted to do that mechanism on his Barrett mod last year. Here's a pic of the rough concept:

BCG return concept.png

That's everything that I can think of at the moment. I've got more plans in store and I'll try to update this as more gets done.


Updates!!! :D

I will post more probably on Sunday after I get some more work done, but I've got enough progress for now that I can share with you guys where I'm at as of now.

Well, the semester has officially started which means that this project is now in full swing. We will start the manufacturing process pretty soon, hopefully in a couple weeks! Alright, time for pictures.

Here is what the gun looks like as of now in a sort of cut-away version.

So I've only created a couple new parts: The buffer spring, buffer tube weights, and a guide assembly for the piston.

Spring and weights:
Buffer spring.png

Guide assiembly (side):
BCG assem 1.png
BCG assem 2.png
BCG assem 3.png

I will be adding one on the bottom soon. Can't do the one on top unfortunately as there's just really no room up there.

So those are the new parts as of now. I still have some other small ones to make certain parts function properly.
Otherwise, I've been adding features to the gun that will actually keep it held together rather than the mates in solidworks. haha. And lets say that there's a fair number of parts and features trying to keeping this thing together. The real trick is trying to hide all of them. ;) Luckily, the 3/8 SHC screws match the circle details on the gun really well, almost perfectly actually. So that was nice.


I've also made pretty significant modifications to the receiver body. Cut out large sections to reduce weight. Built up mounting areas. And added screw and alignment points all over (there's plenty more that I still need to add). Currently each body piece is around 9 lbs using 6061-T6 Al. I'm expecting this thing to be around 35 lbs which is similar to my Socom Gear Barrett, but only a foot and a half longer, and way more cool. ;)

receiver half.png
receiver half 2.png

Note that these receiver bodies are still one piece as of now. I will be splitting them up into two pieces eventually. This will serve to both make accessing certain areas a little easier, but most importantly is to reduce the overall part size. The current length is about 44 inches. And I have a maximum of 3 feet/36 inches to work with. So that will change after I get the rest of the part mounts figured out.

I re-vamped some other parts as well. Since I ordered a complete internal kit for a WE M4, I didn't have to take parts out of my friend's loaner gun and could get more accurate measurements than from trying to get ones with the parts still in the gun. So with that, I remade the trigger box. I've only got a couple pins going in the two holes right now, but I'll probably add more reinforcement to the mounts in a little bit. The trigger also now sits a lot nicer in the well so it doesn't look like it was dwarfed by the entire rifle any more.

trigger box.png

I also secured the pistol grip in with four 1/4 inch screws and the center guide post to prevent lateral movement since mounting a face to a face isn't all that secure. For the trigger guard I will be adding a pocket near the magazine well to hold that flat piece in place.

I extended the buffer system to allow for the buffer weights and keep the 4 inch travel distance and locked it in place with dowel pins. The buffer extension was also lengthened and made so that it is secured into the BCG with a 1/8th inch vertical pin. With the new trigger box, I found that I needed to extend the reset ramp for the hammer to make sure that it is always depressed by the BCG when the BCG is cycling back into the chamber. If not, the hammer would most likely cause the BCG to become stuck and not reseat properly. That also meant that I had to cut out a slot in the magazine top.

buffer system.png
BCG reset.png
magazine 2.png

I have also cut a "Z" shaped channel running through the magazine for the hammer extension to press the valve when the trigger is pulled.

Also finally got a final measurement on the hop unit so I redid that and the mounting system. Basically just added more bolts and pins.
hop 2.png

And last update is the mount for the fake gas piston. This one is just pinned in place.
gas piston.png

Alright guys! That's all for tonight. I'll be having more in a couple days like I said. Almost there!
Itsn't it a beast? Haha. Can't wait to field this.



New Member
Wow, this is awesome. I'm hoping to do something similar in the future using a combination of 3d printed, cnc routed, and airsoft parts. Cant wait to see how this turns out.


WOW that's awesome! Thanks for giving me further detail. I'm trying to plan out a Gas Blowback Halo reach DMR and Sniper. I thought of taking the internals from other airsoft guns like an L85 or something and 3D model a new body. Well, I`m gonna get back to the drawing board. Thanks for posting your cool project!
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