3D Printed 40mm Grenade and Launcher

The US Army RDECOM published a YouTube video on the Picatinny Arsenal YouTube Page about Additive Manufacturing, which includes 3D printing, and the Rapid Additively Manufactured Ballistics Ordnance or RAMBO Launcher. RAMBO, in this case, is fundamentally a 3D printed version of the M203A1 40mm grenade launcher as well as 3D printed M781 training ammunition.

All the components found in the M203A1 grenade launcher, except springs and fasteners, was produced using AM techniques and processes, including selective laser sintering, wax printing, fused deposition modeling, urethane molding and lost wax casting.

The Rambo project was basically a proof of concept demonstration of the Additive Manufacturing, or AM process for the production of military arms and armament. The speed at which using Additive Manufacturing allows something as complex as the M203A1 to be prototyped and manufactured far surpasses traditional, subtractive manufacturing and skips right past any expensive, time-consuming tooling. This in turn allows research and development to make changes in programs and manufacturing far quicker than traditionally.

The .38-caliber cartridge needed for the propulsion of the M781 was the only component of the training round that was not printed.

The 3D printed grenade launcher and 3D printed training rounds were live-fire tested back in October 2016, at Picatinny Arsenal. The testing included firing 15 AM-manufactured rounds with no issues and best of all, no barrel wear. The AM-made system reportedly passed with flying colors.

3d printed parts made with selective laser sintering

Selective Laser Sintering Parts

The printed RAMBO along side its more plebeian issued M203A1

AM Manufactured 40mm Projectiles and Windscreens


Scott is a firearms enthusiast and gun hobbyist whose primary interest is the practical application of gun ownership. In addition to contributing to The Firearm Blog, he hosts and blogs for The Firearms Podcast, a podcast and blog about gun stuff by gun people. Scott is a 20-year veteran of the USAF and been a member of his base, state and the All Guard marksmanship teams. He can be reached via email at scott@thefirearmspodcast.com


  • PK

    Well… that’s an interesting proof of concept, for certain. It’s only a matter of time before we’ve all got the technology at hand to do the same.

    The future sure is interesting!

  • Hellbilly

    ATF will rule 3D printers as prohibited items in 3…2…1… Until then we will be allowed to own 3D printers but we will not be allowed to connect them to a power source unless you’re standing on your head with one arm behind your back; and we sure as heck won’t be allowed to shoulder these printers.

    • Major Tom

      Fortunately, ATF has no jurisdiction over 3D printing technologies. The whole field is largely unregulated owing to its relatively recent invention.

      In the absence of solid arguments to the contrary, it should stay as unregulated as it is.

      (Though Congress in its ignorance of how technology works could easily change that.)

      • M-dasher

        No….3d printing is unregulated because they have no merrit to regulate it….

        3d printing is no different than any other manufacturing process…..regulating 3d printing would be like regulating hand drills and band saws

        • Hellbilly

          The batteries in your sarcasm detector are very weak, grasshopper.

        • Wow!

          Plus 3d printing isn’t even that impressive of a technology for gunsmithing. The fillament is expensive and has to be high quality for a good print, the print needs to be supported, the print takes forever, and it still has to be hand finished to tolerances afterwards. CNC milling and lathe work and sintering is really where progress is being made in the gunsmithing world. 3D printing is more for the people who don’t have the skills or money to run conventional processes and can have a “German Shepard” of manufacturing. Jack of all trades, master of none.

      • roguetechie

        Even if they try the technology is already far too entrenched in the wild.

  • Anonymoose

    This is going to get someone killed.

    • Tinkerer

      Isn’t that the whole point of firearms?

      • DFB

        No, 99% of civilian firearms never will kill.
        The only point of guns is shoot a litle projectile to a high velocity.

        • DFB

          And peoples (no criminals) only point with guns is to self protect,sport and be prepared for foreign enemy or internal future tyranny.

      • Bradley

        Yes it is. Claiming otherwise just supports the whole “you don’t need something that efficient at killing people for sporting use.” Firearms are weapons. They are specifically designed to kill. It doesn’t mean you have to kill something with one, but that doesn’t change the reality of them being weapons.

      • Anonymoose

        Must be why Glocks are so popular, then.

    • Nicks87

      Killed? Nah, just freedom.

    • roguetechie

      It really isn’t anonymoose. The Russians have been printing ammunition and etc for at least a year as well.

      The things we’re going to be able to do with modernized expanded reloading benches that slowly become something more akin to low volume match grade ammunition factories…

      Yeah, it’s gonna be awesome!

      It’s also going to put the lie to the idea that metallic cased conventional small arms technology has reached maturity & or the point of diminishing returns!

      • Anonymoose

        Yeah, but 3D printed guns are not 3D printed bullets.

        • roguetechie

          They 3d print guns and gun parts too…

          In case you have missed the news (totally understandable because not everyone is obsessed with all things “desktop manufacturing” like I am)

          Either last year or the year before that company 3d printed 1911’s for sale which were crazy expensive.

          Then there’s Delta P design who print monolithic single continuous piece suppressors that are ultralight and short and designed to handle brutal firing schedules from mark 18 style uppers in 5.56 and 300 blk and using supersonic ammunition like M855(a1). They also offer 308 versions now too.

          • jcitizen

            I imagine they have to let the metallic part of the cartridge cool down before printing the explosive! HA!

          • roguetechie

            Yeah, I’m really not clear on exactly how it’s done…

            That could get really exciting really fast lol,.

          • jcitizen

            The metal printers I’ve seen usually have the print area full of the metal product in powdered form, and then a laser “sinters” the metal together, then another layer of powder is squeegeed across the printer area for the next iteration.

          • roguetechie

            Honestly there’s been a massive explosion in 3d printing methods that makes it all very hard to keep track of.

            Just in metal printing alone there’s got to be at least a dozen separate and distinct techniques.

            I imagine that over time as this first group of patented technologies start losing their patent protection we’ll see a winnowing down of the current fields.

  • Geoff Timm

    Jay Leno’s garage could do it. Note that there are “lost wax” castings involved here, he’s been doing that for years. I don’t know about the Laser Sintered Metal process. Geoff Who notes the tech is inefficient for production in quantity.

    • SGT Fish

      yes and no. while the actual process of making the part is slower, you can gain a lot of time back because there is minimal set up cost. no need to have whole new machines and tooling built, setup and programmed. so for smaller scale production, it is adequate. But will be a while til it gets faster for long term production, and will stay in the prototyping field til then. But metal sintering can be sped up immensely when you add more lasers and bigger tables to make more pieces at a time. and another plus is being able to make multiple different parts simultaneously

      • roguetechie

        Right, and don’t forget complex internal and surface geometry / the ability to make shapes and entire parts in ways that would be physically impossible to replicate in a part made with conventional tools.

        In the next few years it will become possible to 3d print a part with different heat treatment and even alloys throughout one single contiguous part.

        Combine that with 50 micron scale surface texturing and etc to get barrels and suppressors that almost need a small heater to keep them from getting TOO COLD!! (not really of course, but the statement is calculated to get people interested and thinking!)

        Besides barrels, chambers, suppressors and etc one potential application really excites me.

        That would be “roll your own” custom optics and etc.

        When that field really starts to take off I expect to see whole swarms of garage optics companies and really neat open source base designs which the customer can build upon himself or pay to have manufactured by the garage optics maker of their choice.

        For a variety of reasons I can see a future where companies like lucid vortex atibal and etc form a semi open optics alliance and charge flat licensing fees for individuals or small manufacturers to use their IP in their bespoke optics builds.

        This would create a very positive environment for these companies since their optics would now be “American made” using automated tools and “child proof” software design tools that would ensure a certain quality standard while also allowing customers to mix and match the best parts of multiple designs from multiple companies and hell, you might even see “prescription optics”!

        We could see some very neat, and very cheap optics when it comes to price that could have the big boys worried and looking over their shoulders inside of 5 years from now.

        • iksnilol

          Doubt it, optics are a smidge more complicated what with lenses (you can’t just print a lense, that sucker needs to be ground, at least if you want a good “bespoke” one). Also gas purging, that one isn’t possible with a 3d printer.

          • roguetechie

            Actually the gas purging thing won’t be a problem, and neither will the lenses.

            I’ve got a nearly finished printer that could in theory do both of these things passably with some modification.

            There’s more than one way to skin that cat for certain.

            There’s also a surprising amount of open source optics software and much more out there.

            Call all of that post informed speculation that is HIGHLY dependent upon people thinking out of the box and application of lateral thinking / cadged designs meant for other purposes bent to our will.

            I also don’t imagine “really state of the art” lenses or lense materials for up to a decade from now.

            But, just watch and remember this post of mine when you see the blog entry or etc a few years from now.

          • roguetechie

            Also FWIW, I kinda assume that for the early years part of what the garage manufacturer would do for you is make the key lenses prisms etc for most buyers and their pick n place setup will anchor the lenses for your home printer to essentially print the scope body around it.

            Not only that but I envision something very similar to how things like through pressure hull hatches are installed on submarines in ways where they seal themselves tighter against the pressure hull the more “stressed” they are.
            It really is amazing what clever geometry and engineering are capable of.

          • noob

            try googling for “optical liquid silicone rubber” – it comes out of an injection mold as a finished optical component. It won’t be Leopold glass, but you can make a basic telescope with it.

            and you can 3d print and hand polish or cnc mill the injection mold.

  • Major Tom

    So how much longer until they build fully functional live-fire weapons rather than training aids? My guess says, before this year is out. (And I don’t mean AR receivers that last 10 shots before shattering like the hobbyists have been doing for the last 2-3 years.)

    • M-dasher

      Youre a bit out of touch..people have been printing firearms that ladt a lot lobger than 10 rounds

    • Alex Agius

      Its been happening for years.

      • roguetechie

        Indeed I do receivers and etc that can take phenomenal abuse.

        There’s actually a bunch of techniques which can make very light and deceptively strong components.

        Metal printers will be here very soon, and that’s cool and all, but what has me jazzed are multi machines that can swap out additive, subtractive, and even stuff involving very strong woven or knitted strands of high performance synthetic fibers.

        It’s extremely exciting in so many ways.

        • jcitizen

          Metal printers are already here – I saw a test of a 1911 .45 pistol a few years ago – test was successful!

          • roguetechie

            Oh I know … I’m kinda close to having one of my own.

    • Evaris

      You’re a good bit out of date there, we have 3D printed AR recievers lasting thousands of rounds and .22LR revolvers now.

    • Joshua

      The crew who started that project last I saw were over 10K rounds per lower, it’s not a when anymore, it’s already happened.

  • FOC Ewe

    Just think of the spare parts that won’t need to be procured, shipped and stored at depots/staging areas.

    Just pay for the TDP/licensing….

    • roguetechie

      Exactly, it has potential to be really neat.

    • jcitizen

      This is what car manufacturers are looking forward to. Parts stores will be print shops instead of parts warehouses.

  • jerry young

    So far I’ve seen 3D printing with different plastics from tiny pens to elaborate printers to 3D cement printers that can print a building, what I’m waiting for is the first metal 3D printer that will be able to build fully functional parts, there are already spray welders that replace a thin coating of metal that has to be machined but if someone could come up with a way to print with metal that would eliminate the machining process the possibilities would be endless, you would be able to print metal replacement parts for not only your guns and for your cars but also parts for your home and shop, need a tool don’t go buy it print a copy that could last a lifetime, with the way we’re going this could be right around the corner, someone may read this and think what a great idea and of course the majority will think how crazy it can’t be done.

    • Blake

      Then you’ve been waiting too long. There are plenty of laser sintering printers (like the exact one shown in the video in this article) that print highly accurate models (exponentially more accurate than FDM printers) in a number of different metals.

      • jerry young

        I’m sure there are but there not being made available to the public at least not ones the common man can afford, what I said was basically the same thing that was said when plastic 3D printers first came out and nobody could own them but the extremely rich, I just repeated in my words what I read years ago

        • Blake

          There’s nothing stopping any citizen from purchasing one, they are just pretty expensive. They will never drop down to anywhere near the price of FDM printers. The process is completely different and the components that make up the machine are vastly more expensive. Plus the powder used to feed the machine is insanely expensive too.

  • Colonel K

    The future of illegal arms trafficking isn’t the arms themselves, but 3D printers and a good supply of powdered metal and plastic. Every jihadist cave should have one by Ramadan.

    • jcitizen

      Now that they have been using their own UAVs in Iraq, the terrorist will latch on to this tech as well, but they were pretty slow on the draw for UAVs, so it till take longer I predict.