3D printed gun fires 6 shots - then falls apart

Defense Distributed, a group that is developing free designs for weapons made on 3D printers, tested out a firearm that has a plastic lower receiver made on a 3D printer. It successfully fired six rounds before splitting.

HaveBlue claimed in July to have fired his printed gun hundreds of times, which doesn't seem impossible given the quality of the printing. The part printed by the group is called the lower receiver, which is where a round is received from the magazine. Pictures show it to be very well made, and it appears to fit exactly to the other parts in the gun kit they used.

But the pressure of the recoil appears to have been too much for the "buffer ring," which separates the stock from the upper receiver. After firing just six shots, the gun split in two. It's a serious setback, especially considering they were firing a lower-caliber cartridge than the gun would normally shoot.

3D printed gun fires 6 shots - then falls apart (Thanks, Lew!)

Previously: Defense Distributed


  1. I know what you’re thinking. “Did he fire six shots or only five?” Well, to tell you the truth, in all this excitement I kind of lost track myself. But being as this is a 3D-printed WikiWeapon, the most fragile handgun in the world, and would probably injure at least one of us if I tried to fire it, you’ve got to ask yourself one question: Do I feel lucky? Well, do ya, punk?

    1. Actually, I was thinking about how to plan the perfect murder and how that might involve 3D printing…

      1.  Still wouldn’t compete with the Alfred Hitchcock Presents episode called Lamb to the Slaughter (starring the lovely and talented Barbara Bel Geddes ;)

  2. That might not seem like a lot. . .  but how often are you in a situation where you need more than six people dead?

      1.  No, you can do that in 4 bullets.  By the time the second cello goes down, they’ve all stopped playing.

    1. If you’d ever fired a gun before you might understand that 1 shot does not necessarily equal 1 kill, or even a hit. Firing a gun accurately requires skill and fine motor control, both of which get all kinds of screwed up when your body dumps adrenaline into your system. Firing a gun when you’re jumpy from the loud noises is difficult, firing a gun and doing so accurately when somebody is trying to kill you is significantly harder. 

      This might be a clue as to why police officers (who tend to have lots of gun-carrying backup) feel compelled to use sidearms that carry 15 or more rounds.

  3. … Is that really the way to test such a thing? Put your face up against it? 

    A vice, a mechanism to manipulate the trigger, no one around.

    I know I know, just teh lower receiver, all the danger is elsewhere. I too won’t feel a thing for the nimrod that prints a whole weapon and tests it on their face. So I guess I’m okay with it.

    1.  I was thinking the same thing.  At the least, I’d be inclined to use some kind of MythBuster’s jerry-rigged set up for testing any weapon prototype, let alone made of plastic from a 3D printer.

    2. The lower receiver, which is the printed part here, isn’t where detonation happens. That is taking place in the upper. So the boom is taking place in a factory-made chamber, not a homemade printed part.

      The lower houses things like trigger assembly and selector. I think one of the potentially scary issues here is that the selector is where the options for “1, 2, 3, full-auto, safe” live.

      One may, IIRC, purchase uppers all day long with no registration because the lower is really the technical part where the magic happens. Uppers don’t even possess serials AFAIK.

      1. aight now, yall got to read to the end of my short post to avoid telling me that it’s just the lower, which is what’s at the end of my short post.

      2. You’re right.  The receiver (lower receiver in this case) is the key.  In fact, in the latest Sportsman’s Guide catalog, they have a complete AK-74 receiver that you can buy as a part without a license, since it’s classified as a blank.  All you need to do to put the rest of the parts in is drill a few holes and put in a couple of pins.  The receiver is the only part you need a license to buy.


    3. I couldn’t believe this either! They must have had a significant amount of faith in the preciseness of the printer used.

      No offense to these gentlemen, but if you’re gunning (heh) for the Darwin award, this is a good way to do it. 

  4. Note too they used a 5.7 round, not the standard 5.56. The 5.7 is a much lower powered round. Had they used with 5.56 ammo, the recoil would have been much more and led to an even earlier failure.

  5. I spent a year printing molecular models on a high-end 3D printer (Objet).  Unfortunately, there are significant limitations in the materials able to be printed.  Also, old-style manufacturing processes can orient grains, remove inclusions, harden surfaces, and otherwise maximize end strength (particularly for metals, but also somewhat for polymers).  Still, there is a lot that 3D printing can do that is not otherwise possible, and it may just need some tweaking in the part designs, and maybe better post-processing of materials.

  6. Not surprised really that this is where the lower would fail. I can imagine however how a design change could remedy to that, but that would require a fatter ring, and/or printing an integrated buffer tube and buttstock, making all three parts one piece. Even better, join the pistol grip with the buttstock, and leave a thumbhole. Now you have an odd-looking, almost featureless-like lower assembly, but I’d bet it will hold longer than 6 rounds.

  7. Does anyone (in the firearms industry proper) currently make this part from polymers? I know a lot of handgun manufacturers make extensive use of, presumably injection moulded, polymers in the receivers and slides. Is this also true of this kind of rifle? If not, that might be a hint to the makers of this printed part regarding the design. As arnaudh pointed out, redesign of the part with the loads and material limitations might yield a better result.

    1. Yup, NFA, ATI and Plum Crazy do.  I have the NFA with over 3000 rounds through it and the only thing that broke was a little pin which has been replaced with metal now.  

  8. It isn’t a gun that they printed, it’s the lower receiver. Geebers. A fully 3d printed gun would blow apart on the first shot due to the physical properties of plastic.

    1. Huh… Actually, Smith & Wesson’s lower receivers are machined out of aluminum, like most metal lower receivers. But there are many manufacturers also making lower receivers out of polymer or carbon fiber.
      It’s only a matter of time for the lower receiver design to be reworked successfully to work with 3D-printed material.

  9. Looking at that vid again, I think there’s good reason to believe it failed at fewer than 6 rounds. He had the butt pulled into his shoulder pretty tightly. It didn’t fall off until he lowered the weapon, so it’s possible that it was held together for a few shots just by the pressure he was exerting on it. 

    Also, notice that at the very start of the clip, the textover clearly shows the word “reinforced,” meaning they thought this particular receiver was overbuilt to be sturdier than the standard printing. Which means that the product they tested was even shittier than it looks.

  10. How many shots do you really need in order to assasinate somebody with a weapon you’ve made out of plastic in order to sneak it past security?

    1. Wow.  Way to be completely ignorant there.  It is currently IMPOSSIBLE to sneak a gun past a metal detector.  You can make a receiver from non-metal parts.  Magazine too (well, you still need a metal spring).  Trigger assembly — probably (with metal springs).  The barrel (you know, the thing that holds the bullet while it is being fired) MUST MUST MUST be made of metal.  The chamber end has to withstand several THOUSAND PSI.  Also, the bolt/slide should also be metal.

      Sheesh.  The whole “plastic gun” thing started to make the rounds when the first Glock was first introduced.  The myth is about as true now as it was back then.

      1. It’s true, all attempted assassinations failed. Strangely all assassinations succeeded. The people going for the attempted ones really should have read up on this shit beforehand.

        1. Failed and successful assassinations both qualify as attempted assassinations.  Or can you propose another set that includes both?

          1. Fucking logic. It’s not in the bible.

            /and I got three “likes” so I’m not the only stupid bastard, at least.

  11. the problem is using a design that was made for metal, and printing in plastic. The whole thing needs to be redesigned to meet the strength parameters of the material. Not too hard, but need thicker walls everywhere. 

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