Did I mention wasting time and money yet? Also guns.

In my last post, I showed a video of a lower being printed out of PLA so it wouldn’t warp. I decided to print a new one out of ABS in order to actually have it be strong enough to use once it was assembled.

This is by no means a “how to” or even an assembly guide. I just wanted to post a shitload of pictures.

At this point, it started warping so I put a little epoxy around the edges that were pulling up. It’s a stupid solution to an even stupider problem, but it totally works as long as you don’t get it on the top of the print.

With all the support material, it weighed 207 grams. 100% infill, 0.35mm layer height.


Clearing out some of the support material.

Done. Ish.

After removing all the support material: 93 grams.

Step Zero: Install the bullet button.

Living in California means dealing with bullshit laws like the assault weapons ban. This little nub that keeps you from removing the magazine without a tool completely sidesteps all of the rules. The California DOJ hasn’t specifically said that this is legal, but they have also declined to describe it as illegal. Whatever the politics of it are, it’s retarded.

Step one: Split the fucker in half trying to thread in the buffer tube.

I knew it looked a bit tight, so I drilled it out a little bit where there had been a very SLIGHT warp in the print. It looked like it was doing just fine, if a little stiff. Suddenly, POP. The print diameter is 2mm smaller than the buffer tube diameter. I have no idea how that happened, as everything else was near perfect and required minimal trimming.

Step Zero part 2. Install the bullet button in the lower you decided not to use.

Since I had all the parts laying around and a printed lower just sitting there, I decided to assemble it anyways. I deemed it too weak to test fire before I assembled it, but I figure why the hell not.

Installing the bolt catch.

Sadly, the sprint on the bolt catch isn’t moving freely right now so it probably needs to come out before actually test firing it. I had to heat up the holes to get the roll pin in, and it’s probably going to break if I take it apart.

Fuck this goddamn detent.

THAT LITTLE PIECE OF SHIT SILVER THING CAN SUCK MY TESTES. Seriously. It’s on top of a spring, and you need to depress it all the way in to get the pivot pin in place, it only fired itself across the room once, and luckily I found it.

Groovy fuckin’ trigger guard.

I guess it’s a benefit to have that bend in there somewhere, otherwise Magpul wouldn’t have made it that way, right? Gun people don’t do silly marketing things, right?

Clearancing the side for the takedown pin.


Trigger and hammer installed.

I didn’t get any pictures of the install crap, but it’s pretty simple. The trigger is pinned in on one pivot point, the hammer on another with a second pin. It’s actually a simple gun (in this part).

Magpul grip installed.

I still find the stupidest thing ever that the gun needs to be cocked in order to put the safety on. Also, the spring for the safety selector detent (the part that makes the satisfying CLICK when you go from safe to fire) actually goes in the grip. There are more than a few things here I’d personally consider design flaws.

Hey look, a buffer tube WITHOUT CRACKING.

I used the exact same model for both lowers, this one I printed vertically, the other lying on it’s side. Somehow that made it smaller.

Stock installed.


Luckily it’s “safety orange” so it can’t possibly go wrong. It’s uncocked with the safety off, and I pulled the spring out of the buffer tube, just because I’m paranoid about springs under pressure on the plastic.

The idea now is to use a 9mm upper to test fire it, under the hopes that the 9mm will put less pressure on the buffer tower and someone is willing to let me borrow a 9mm upper to test fire this monstrosity. One of those two things is more important than the other. I say the chances of it suffering catastrophic failure on the first shot to be around 80%. I need to find out if there is something cheaply available like a ransom rest, but for rifles. Or a vice and some string. Either way, the important part is getting it on video. And not damaging the parts so I can reuse them later on a real lower. Safety third.


8 thoughts on “Did I mention wasting time and money yet? Also guns.

  1. Permalink  ⋅ Reply


    November 18, 2012 at 6:57pm

    Got an STL file for that?

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    November 18, 2012 at 7:17pm

    Have you considered doing something like fiberglass/epoxy on the weak points?

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    November 18, 2012 at 8:13pm

    The bend in the trigger guard does serve a purpose — it makes it easier to use the firearm while wearing gloves — especially “heavy” winter gloves. The stock trigger guard is straight, and it can get in the way.

  4. Permalink  ⋅ Reply


    November 18, 2012 at 11:34pm

    Awesome. Looking forward to seeing the rest of the build.

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    November 19, 2012 at 7:14am

    This looks like you could make some really spectacular nerf style guns though.

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    November 19, 2012 at 10:56am

    For getting that stupid detent pin in, I inspected it very carefully, made a good mental model of what needed to happen, and did it under a blanket. That way, any sudden release of parts would not result in 3 days of scouring the corners of the house looking for it.

    Just figured I’d throw in my 2-cent method for doing this. Good luck! Looking forward to the results.

  7. [...] the ground up. Another person has demonstrated that commonly available 3D printers can be used to manufacture AR-15 lowers. Since lowers are the registered part of the firearm and therefore the only part you need to buy [...]

    • Permalink  ⋅ Reply


      December 11, 2012 at 8:42am

      Thanks guys, I just about lost it lkooing for this.

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