Learn About Historic Firearm Design With A 3D Printer

Over the last century, very little of the basic design of firearm cartridges has changed, but the mechanics of firearms themselves have undergone many upgrades. The evolution of triggers, safeties, magazines, and operating mechanisms is a fascinating field of study. Hands-on experience with these devices is rare for most people, but thanks to people like [zvc], you can 3D print accurate replicas of historical firearms and see how all the parts fit together for yourself.

[zvc] is slowly building up a library of 3D models, with nine available so far, from the Mauser C96 “Broomhandle” pistol to the modern M4 rifle. Except for springs and some fasteners, almost every single part of [zvc]’s models are 3D printed, down to the takedown pins and extractors. With the obvious exception of being able to fire a live round, it looks like all the components fit and work together like on the real firearms. None were ever designed with 3D printing in mind, so a well-tuned printer, lots of support structure, and post-processing are required to make everything work. The surface finish will be a bit rough, and some smaller and thin-walled components might be susceptible to breaking after the repeated operation or excessive force. The models are not free, but all prices are below €10.

These models do demonstrate one of the real superpowers of 3D printing: functional mock-ups and prototypes. The ability to do rapid iterative design updates and to have the latest design in hand within a few hours is invaluable in product development. [Giaco] used this extensively during the development of his kinetic driver. When you buy 3D printable models online, always make sure what possible pitfalls exist.

25 thoughts on “Learn About Historic Firearm Design With A 3D Printer

    1. I’m no expert but I reckon the metallurgy would be the sticking point. i.e. If you machine a spring then that will deform under load. springs have a specific method of manufacture. but you could do most of it i reckon.

  1. I advise the people printing these designs to be careful! You can very easily run afoul of the BATF if your 3D-printed receiver can be used as part of a viable firearm. If, for example, you print an actual M16 or M4 lower capable of accepting fully-automatic parts, you can and will get nailed on manufacturing a machinegun. It won’t even matter if the gun can’t fire, they can bust you on “constructive intent”.

    Lord help you if you print a suppressor that can fit a real firearm and provides suppression, even for a single round – they have zero sense of humor or understanding about that.

    1. You probably shouldn’t comment on things you don’t understand. To begin with, the lower that was printed didn’t have the infamous “third hole” that would make it a “machine gun” regardless of the components installed. Nearly every component between an M16 and an AR15 are the same. There are no “fully-automatic parts”, but there are parts (including coat hangers) that can be used to make a semi go full – which is what gets you your felony when and if you get caught… none of the printed components here even remotely resemble any of these components.

      1. I advise you to re-read the comment. I didn’t say that these designs were problematic – what I did say was that if you print an M16 lower that includes the fully-automatic features (third hole, fully-milled pocket without the step) that the ATF can and will classify that as a machine gun.

        The notion that there are no “fully-automatic” parts is wrong. While the full-auto M16 bolt will function just fine in a semi-only AR15, there is an actual physical difference between the two. The ATF doesn’t care about that one, since it doesn’t make any functional difference by itself without the other parts and the “finished” full-auto receiver.

        The FCG of the full-auto M16/M4 does in fact have different parts – the hammer/sear is different, the safety selector is different.

        If the receiver can accept the three-round burst or automatic sear, it is a machinegun in the eyes of the ATF. FFS, the ATF classified a shoestring as a “machinegun”. If you happened to print a receiver with the internal features, and happened to own the burst/auto FCG parts, you have what the ATF calls “constructive intent” and that is good for federal charges.

        This does not include and is totally separate from subjects like the lightning link, or other parts designed to make a semi-auto-only AR15 receiver fire fully-automatic.

          1. they are interchangeable, but not identical.

            The M16 bolt carrier will have about a 2″ closed section at the rear that actually trips the auto sear in full-auto fire. Semi-auto versions have either a reduced closed bottom section (about 1/2″), or a completely open bottom (made so that an adapter to M-16 configuration cannot be installed).

            Another difference in the bolt carriers is the additional metal removed on the underside to expose the collar of the firing pin. This is intended to catch the hammer and prevent firing if the carrier is not fully forward when the hammer releases. This occurs if the hammer is “riding” the carrier back (i.e. no auto sear is holding back the hammer). On the M16 bolt carriers, the firing pin collar is not exposed.

            (from here: https://ar15armory.com/forums/topic/162644-full-auto-vs-semi-bolt-carrier-group/ )

            you can legally use either bolt carrier, and either will work in a semi-auto AR15. Just don’t mill out the full pocket, and don’t drill the 3rd hole. doing so will allow the fitment of the full-auto sear parts, and thus “manufacture” a machine gun.

            seriously, stop trolling, and stop giving people bad information. it’s an excellent way to get the attention of the BATF, if that’s what you want, though.

    2. Not true. Federal law (including BATF rules) does not forbid an individual building their own firearms. Those firearms cannot be transferred to another individual, however. Now, if said individual lives in a repressive state that believes they can pick and choose which parts of The Constitution they want to abide by (like California), they may run afoul of state law enforcement. It’s happened. The aforementioned state also has new laws about to be implemented that seek to make building home made firearms extremely difficult (and, they hope, impossible); requiring serial numbering of all firearm parts, background checks for each piece (of course paid for by the purchaser), and extra taxes and fees above and beyond normal state sales taxes. This is, of course, intended to make firearms purchasing/ownership prohibitively expensive. It is also unconstitutional (2A applies).

      1. ATF rules specifically note that individuals have the rigth to build firearms, subject to certain rules. A simplified version would be “any firearm that you, personally, can legally own”.

        You could build a machine gun (post sample) if you had the proper licensing, but the trick there is that if you let your licensing lapse, you have to turn in or destroy the machine guns. This licensing is pretty expensive, and there are a lot of rules around it.

        You couldn’t legally build a firearm if you were a felon prohibited from owning firearms. Even that isn’t absolute, as black powder muzzleloading and percussion cap guns aren’t considered “firearms” by the ATF, and most states.

        For other weapons not regulated by the ATF, that do not require special licensing, (your usual and common pistols and rifles), then yes, you can in fact build your own firearms, as many as you want. You can even sell them (with the fine distinction that you can’t build them as part of a business of selling them)

        Some states regulate this behavior because the Constitution is just a piece of paper to them, and one they’d wipe their rear end with if they could.

        1. Said licensing also puts you under the BATFE’s microscope; they _really_ don’t like people making full-auto firearms, especially people working out of a home shop. (I seem to recall them cracking down on ‘kitchen table’ FFL 01 dealers for similar reasons, but that’s just hearsay.)

          As far as making your own firearms and then selling them? that’s a grey area, a tarpit, and a minefield all at the same time. And you can’t make them first then get the licensing. As noted before, BATFE agents have no sense of humor about such things, and a lot of them also don’t have allow for any leeway.

    1. Can BATFE force take down that content? Not sure what the legal basis would be.

      But Sue Sulio is unfortunately correct. I am sure BATFE will not care that the material is a poor choice for a real gun.

      1. No, the BATF won’t take that content down. The State Department lobbied to ban it under ITAR a while back, but lost that court case. They’ll be back, though.

        You can make make plastic replicas as long as they can’t be used with existing hardware to make a machine gun. There’s probably some wiggle room there, but the phrase “don’t poke the bear” applies. However, you can always write the BATF and ask. They’re generally fairly helpful, but you might wait a while for an answer.

        Various airsoft manufacturers got in trouble a while back for making AR and Glock lowers that were interchangeable with the real thing. As long as that’s not the case, you’re *probably* ok.

        Here’s what the ATF regulates:


        The interpretations of what the various regulated firearms are is the part that gets people into trouble. For some light reading, try here:


        Note that if you’re not living in the US, these don’t apply to you, and other local laws apply.

        1. From that document, here is what the ATF considers a “machine gun”:

          Any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot without manual reloading, by a single function of the trigger

          The frame or receiver of any such weapon

          Any part designed and intended solely and exclusively or combination of parts designed and intended for use in converting a weapon into a machinegun, or

          Any combination of parts from which a machinegun can be assembled if such parts are in the possession or under the control of a person.

    1. I hear you. Up here in Canada, a local 50 year old man was arrested and charged with printing firearm parts (and soliciting printing them). Very good chance he’ll get some serious jail time.

      1. I think that guy got screwed pretty hard – it looks like he just printed all-plastic firearms, but it’s basically what I am suggesting here – be careful. don’t make parts that can be used with functional firearms parts unless you have an understanding of the local laws.

        those plastic suppressors probably wouldn’t have lasted past the first shot.

    2. If you are in NSW you are not allowed to possess files for the manufacture of firearms or parts thereof. The state banned them after the NSW Police 3D printed the infamous ‘Liberator’ pistol in a 17 hour run and it exploded when firing the first round.

  2. The files are not illegal. The printing of these files are not. Please note that the manufacture of fully automatic firearms is illegal. You can only build one if fully allowed by government. Any type of Full auto will land you in jail if it is capable of being fired. But having the information to make the firearm is not illegal. People make suppressors all the time, where they can register it, same with the firearm. You have a choice. Also the plastic suppressors last, the Bantam suppressor can handle 5.56 and is full auto rated as well as 3d printed. Also most of these files have been around for some time. They may be refined here but they have existed since about 2015.

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