So I recently got into hunting, and decided on an AR-15 for my deer and hog rifle. But me being me, I wanted to

build it myself. I wanted to design and make as many parts as I could starting out as a total newbie. This will be my first rifle, and first weapon I have built. But I am not new to machining, design, or 3d printing.

I didn't try to make it the lightest, or the most accurate competition gun, or Tactical defense killing machine.

It was really just a learning process and building something I thought would work well and look cool.

Key points in design for me were reasonably light but not giving up too much durability. I did try to achieve as

minimal kick back/recoil as possible. I have removed certain normal features that most rifles would have. Maybe a

little controversial. But I built this rifle for me and me only. Not for sale, trade, or borrow. Anything I

deleted, I can easily add in at a later date if I feel the need.

So... On with the details.

Total Cost: Under $700 including cost of printing.
Total weight: 3lb 12oz-ish including empty magazine. (I'll get a final when complete)

Parts I designed and built:

- 3d Printed Lower Receiver
- Carbon fiber tube as buffer housing & barrel cover
- 3D printed shoulder rest
- 3D printed grip (Not my design, I only modified it)
- 3D printed magazine catch assembly
- 3D printed flash suppressor (Pressed in Aluminum threaded bung)

Purchased Parts:

- Anderson Manufacturing Lightweight Sport AR Upper Receiver.
- Mil Spec Barrel Nut (Got one designed, just not machined yet)
- Light Weight AIM AR .223/5.56 NiB 9310 MPI BCg.

*Machined gas key for gas regulation. Machined bolt carrier for charging handle.
- AIM SSTAT Single Stage AR Trigger (Definitly not a lightweight choice)
- Pro Mag RM5 Roller mag 5 Round, Technapolymer. (Law states I can only hunt with a 5 round Mag)
- Faxon Firearms 14.5 Inch Pencil Ultra Lightweight Barrel
- Battle Arms Development Low Profile Titanium .625 in. Gas Block
- AIM Mid-Length AR Gas Tube
- Buffer Tube = Carbon Fiber Tube ~ 1.00 ID x 1.25O OD (Roughly Anyways)
- Taccom Ultra Lightweight Carbine Buffer
- Taccom 10% Reduced Recoil Carbine Length Buffer Spring
- Misc. Hardware, springs, and split/roll pins (No off the shelf AR parts here)

I have begun final assembly and finishing up the last few modified parts. So on with the pics!

First Pic if a Defdist Printed Lower. This is the Lower receiver that made all the noise a few years back and put

3d printed weapons in the lime light. I decided I didn't want to just print someone else's design. And started my

own.

Here are a few various images I took screen shots of during the design on this. I didn't plan on doing this build thread in the beginning, or i would have had better images to show the progress... Man many many changes to my design were made throughout this process.

This is now many hours and 3 lower receiver prints in and not being satisfied with the result completely. But it was coming along. Design enhancements and fitment issues are getting better.

Now I started working on some of the mechanicals. I decided to make my own Mag catch assembly. Here is an image from SolidWorks. It's currently printed and installed. Works great!

Taking a break from 3d images and plastic crap. Time to put some time in on the Mill.

I decided to go with an Non-adjustable gas block. Mainly for it's small compact size. So, I needed to machine my gas key for adjustability.

This is how the rifle sits currently. Buffer tube and Shoulder rest are installed and NOT removable. Mag catch assembly installed. Trigger installed with .156" Split pins. Grip installed. Upper receiver test fit and all hardware test fit done. Assembly is going well.

OST

Why the weird pistol grip?

Next up. Machining the BCG for Right Side Charging Handle.



To Be Continued...

How much work are you having to do to the printed parts before they are ready to use?  Are you having to redrill holes or do any work to hold the dimensions?
I ask b/c I'm not getting the level of precision I would like out of my printer compared to milled parts.  At best I've only been able to hold .004 in the X and Y dimensions.

I wouldn't suggest trying to print a muzzle device, insert or not.  I've seen plenty of steel muzzle devices fail.  They are expose to high pressure and temperature.  Best case scenario it is eroded over time, worse case it breaks and high velocity fragments go random directions.

Do NOT expect better than .004" of accuracy from a 3d printed part. Unless you have something in the industrial price range.

I did VERY little to finish the part to be ready to use. But after printing a few. I was able to see where shrinkage was happening and adjust for it. It's best to let holes for hardware be small and ream them out if you want a super tight clearance fit.

What material are you printing with? What parts are you printing?

I wouldn't call it weird. I would call it different or uncommon. It's not my original design. There are others that are similar as well.

Original designer:   https://www.thingiverse.com/thing:2659235

but I chose it for a few reasons. One being able to be a lower overall profile if in the prone position laying down on the ground. Possibly crawling... another reason I thought it  looked cool! lol...

Interesting project.

You do realize that your fairly light weight and stated goal of having minimal recoil are somewhat working against each other? I have messed about some with light ARs that belonged to others and have decided that for me I can't hold and shoot a gun that is under 6 lbs worth a darn offhand. A 4 lb AR would be the last thing I would try and hunt with

I would be surprised if that grip works out but ,hey, one screw and you are back to a standard grip.

Did I miss what barrel you are using?

Of course just because something doesn't work well for me doesn't mean it isn't something you want.

Keep us updated please

Hopefully between tuning the gas at the gay key. Low mass BCG and buffer spring combo will reduce the recoil effect. BUt if if works in the opposite direction...ehh. It's still a .223

I have had the rifle fully mock assembled. The grip is surprisingly comfortable as I played around with the rifle like a kid with a new BB gun. I don't plan on changing it as of right now. Maybe some field time will change that....?

Barrel is listed at the top under the Parts Purchased list.

So you have a tax stamp already approved for this?  Because I can't imagine a 3D printed muzzle device ever being permanently attached through any means, aluminum insert or not.

The problem is in the wording. I am no Lawyer, or weapons specialist. But no where does it say what material it can or cannot be made from. I can just as easily remove a pinned or set screw bound device just the same as a polymer, plastic, brass, carbon fiber, wood, unit.... Material does not matter here (i think). The method of attaching it is the definition of "permanently attached".

The problem is in the penalty if BATFE claims you get it wrong.  Up to 10 years in prison, $10k fine, loss of your 2nd Amendment rights.

1000 degree silver solder or a steel pin welded in place is what is viewed by BATFE as permanent.

Well... I've been debating on swapping the suppressor for a larger silencer I have modeled. The silencer would be made from metal.

I was trying to avoid the legal difficulties with the suppressor. Guess I failed at that. lol...

And if you weld or silver solder that aluminum "insert" that's "press fit" into the plastic muzzle device, then that insert is the ONLY thing considered permanently attached.  The rest of the device (especially if it shatters when you shoot it, which is 6:1 the likely outcome) is not considered part of the barrel length.

Either use a 16" barrel (it's literally a 4-ounce difference between the 14.5 pencil and the 16" gunner) or have a proper muzzle device pinned and welded.  Faxon even offers some pre-completed, with a small enough diameter you can fit gas block and barrel nut over them.  That may be the best route to go.

I still want to test the functionality of a printed suppressor for future design enhancement. Which is what everything on this build is. Prototype parts for me to enhance and upgrade as a hobby. I will be removing purchased parts for parts I have designed and manufactured one by one until hopefully, all of the parts on the build are my own. Also, for 3D printed suppressors, I am by no means the first. Do some searching, it has been done many times already. With pretty good success. Sure it will wear quickly. But shattering/exploding is a non-issue in this case. Unless of course design flaws are an issue.

I do have this if need be...

Setting up a new never used BCG and Upper Receiver in the vice just doesn't feel right...

Tapping 4-40 in case hardened steel.  

This is not the finished product for the Charging Handle. But very close to what it will look like. This was just printed for a test fit and clearance check.

Test fit good to go. locks back with no issue or interference.

Bench test...

Ascetically - I wonder if the charging latch would look better if you followed the contours of the deflector.  Would also lesson the snag potential.

Awesome, if not wonky, build!

That deflector has since been machined down some. The rifle is fully "mock" assembled right now waiting for a few changes to things I want to make better.

I definitely take "wonky" as a compliment. It's supposed to be out of the norm, but function normally.

Might as well machine off the rest of the Brunton Bump and add a top bit to your charging handle for cases to bounce off of.  What happens when the bolt carrier gets hot?

I'm not worried about the heat right now. I have 3d printed parts inside my cars engine bay. For reference how hot it might get in there. I live in Florida, and the car has a Twin Turbo V6 packed in tight. The 3D printed parts are mounted to metal parts and are relatively close to the turbo. Couple thousand miles so far with no obvious sign of fatigue.

If heat did become an issue, i would either print in a different material or machine a handle from aluminum.

Very cool thread. Please keep the updates coming.

Pretty impressive.  !!

Very cool

Well done overall.  What the hell size bolt did you use for that mag release?

I honestly think you could do a better grip.  I've roughed one out that mimics the p90 grip and I'm certain that it would be a lot better for ulnar deviation in your wrist.  The shape would also lend itself to being more low profile/snag free than a standard grip.

Good!  Intended as such.  

Everything I have made on this rifle is a prototype intended for real world use. So, I expect to make changes as I use it and find areas needing improvement. But, the grip is one that has a purpose. If I find myself crawling in low grass. The lowest profile possible is a benefit. With a 5 round short Magazine and the "Tactical" low profile grip, the rifle is very slim overall. As I hold the rifle, it feels extremely easy to move around with. Seems smaller than all other AR's iv'e held.

I think the screw size for the Mag Release assembly is 4-40 x .750 Long. The spring I chose to use feels perfect. A normal off the shelf Mag Release spring would not have fit.

So I Milled down and added a radius to the shell deflector. Looks better (to me) and now I have no pinch point while pulling the bolt back.

I only really need to make a barrel cover/hand guard now and it will be complete. That and decide on what  to do about the flash suppressor. To keep the one I have installed, Use the Titanium one I have sitting, or make something else… Anyways. Here it is mock assembled. Surprisingly balanced!
Notice it balances on its own whether resting on the Magazine or vertical on the shoulder rest! No trickery.

And the other side.

Pictures can be deceiving but..

It looks to me like you will have to have really long fingers to reach the trigger, that is if you grip it the way I would imagine someone might.

What epoxy are you using on the carbon fiber buffer tube and where did you source the buffer tube?

I admire the tenacity and creativity, but I hope you plan to test it in a wood vice with a string on the trigger...
That's what I've done anytime I built something out of the box....

The 3d printed ABS suppressors are fine for .22LR for a while, but the first round of 5.56 you put through that brake will probably send it downrange in pieces.

For some side notes:
The adjustable gas key needs some sort of locking on the set screw, the Sun Devil and RCA keys use double-stacked set screws to prevent it from backing out.
The carbon fiber buffer tube, how are you retaining it in the lower and the stock plate?  You may not realize, but during normal operation the buffer can slam into the rear of that buffer tube with pretty significant force.

Just some things to look out for when you get to the testing phase.

I have "normal" length fingers...? Maybe on the shorter side really. And I reach it just fine. That was a worry in the beginning that I tested on my first of the 4 total lowers i printed.

I was originally worried in the beginning about firing it. But, now that I have a basic understanding of how the rifle operates. I don't believe there is anything to worry about so long as the ammo itself has no defects.

The bolt loads the round into the barrel extension. The trigger is pulled sending the firing pin into the primer only leaving the bullet to go in one possible direction. Through the barrel and down range.

*** I want to add I am still very much a newbie. If there is another reason I should take extra precaution, I would like to know! I do not claim to have great knowledge! ***

I'm working on a solution to lock the gas key currently. I haven't come up with anything I am satisfied with yet.

The Carbon buffer tube is held in with a very strong 2 part epoxy. Strong, not hard. That's important. It should have some flex as to not make it brittle. the shoulder rest is a press fit. It also has a set screw from the top and bottom securing it in place. My plan is to regulate the gas low enough that at first shot the second round may not be chambered. Then adjust it until it chambers a round. Ideally, the buffer will never bottom out.

This is an older picture I took early on in the build. Pictured is the 2nd of 4 lower receivers.

But it shows most of the parts in use not yet assembled. Low Mass BCG, Reduced recoil spring, and two sided light weight buffers. 1 piece trigger group. etc...

It's threads like these that make me wish I had time, talents, and tools

Time: I start my prints before bed, done by morning.

Talent: YouTube and Google have all the information you ever need. Research while you poop.

Tools: The price of my equipment will pay for itself, literally all of my "tools" heave earned more than I have paid for them. They also have made parts for myself which probably add up to more than twice the value of ALL of my equipment.

Basically, I'm saying.... Anyone can do it. Seriously.

See a few notes above in red.

Also, I see your 2-piece lightweight buffer setup, what made you go for that over a single piece?
I would assume those pieces are ABS or delrin, but you need something softer to absorb the impact if the buffer were to bottom out in the tube, so it won't hammer out the stock plate.

Two flush-fit mags for your consideration:

https://promagindustries.com/ar-rifle/82-ar-15-223cal-10rd-flush-fit-blue-steel-magazine.html

Have not used this one - I have their 5 round flush-fit, works fine.  Despite their terrible reputation, I have yet to experience a ProMag failure, and I have 3 or 4 of em in 2 different platforms.

https://www.thermoldmagazines.com/ar-15-m-16-10/

Thermold sent me a half-dozen of these for T&E.  They work fine.  The baseplate fits just outside the standard AR magwell.

I'm going to suggest you rethink your buffer tube.  If you knock the rear end out of it under recoil, the gas key is going to smack into the top of the buffer tube boss and you'll have to reprint your receiver.

I think you need a plug securely epoxied in the back of the buffer tube - a press fit & screws are not going to retain the buffer, buffer spring, and bolt carrier at operating velocity.  Alternatively, you could thread it internally or externally and screw in or on a plug.

I wouldn't use a string to test fire it, but that's me.  If your bolt carrier is in spec, it won't fire out of battery.

How about if the stock/lower flies apart, or the muzzle device peels back/detonates

Eye protection.  Muzzle brakes are a hazard to hearing protection anyway, so he'll be better off w/o it.

My Mk 7 prototype stock broke on the 2nd shot during its one and only test of 12 ga 3" 00 buck recoil.  I fired 3 rounds.  

Considering he's using a 14.5" barrel, I have a sneaking suspicion he won't.