DIY barrel rifling using salt water, electricity and a 3D printed jig

Here are pictures of a preliminary setup for creating rifling grooves in a piece of steel tubing by using a 3D printed spiral insert, lots of salt water and a battery charger. Electrochemical Machining is a process whereby metal is removed by passing an electrical current through a solution, the insert in this case exposing the specific areas to be ‘cut’ during the process. The results are quite interesting and certainly open up some possibilities for homebuilders.

“This is Jeffrod’s ECM jig, 5 inches long with a 0.813 diameter printed in black PLA and setup for 4 grooves using 26 gauge steel music wire for the electrode.”

3Dprintedriflingjig1

“ECM jig hooked up to a Schumacher SE-82-6 12 volt manual battery charger ([email protected]/2a; [email protected]) at 6amps for 10-15 minutes. Note: this Rifling machine has no moving parts.”

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The first test results showcasing the ease with which material can be removed in short order:

ECMrifling

Salt, 12v battery charge, water supply (orange bucket) and rifling jig setup (green bucket).

ECM-rifling-setup

The results of a four inch twisted pentagonal cylinder with five grooves:

EDM-Rifled-Barrel

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The complete process can be viewed here along with two rather long videos explaining everything above.




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  • Giolli Joker

    This is extremely cool.
    I’m all for mechanical systems, but this is great.
    Moreover it should allow use of harder steel alloys for the barrel.
    If done correctly it could actually allow a very good result.

    • More importantly, you don’t need to stop at steel. The USAF investigated using ECM to rifle various “super-alloy” bore liners during the 25mm GAU-7 program. This led to erosion testing using MG3 and M60 converted to .220 Swift and .22/30-06.

  • lowell houser

    This is just amazing. Low investment solution for a big homebrew problem.

  • now chrome line it

    • aka_mythos

      Similar sort of process, just in reverse. Just a case of using a chromium saturated acid bath instead of whatever acid they used as the electrolytic, masking the exterior of the barrel, switching the polarity of the barrel from being the anode to cathode… while compensating for the thickness of the chrome when the barrel is rifled.

  • Heartbreaker

    This is pretty amazing. It would be interesting to use it for specialized rifling such as progressive (or gain) twist rifling.

    • JeffreyRodriguez

      Spot the person who knows a *bit* more than the average bear. They ask about gain-twist rifling.

      I was thinking the same thing, and it should be doable. Don’t tell the guys who cut that stuff today, they’ll have a heart attack 😉

    • Forest C. Adcock

      That was my first thought as well. It looks like it would simplify increasing the twist rate near the muzzle greatly.

    • RocketScientist

      Since it appears he used ECM to make the bore and even chamber to their final sizes, looks like it’d be fairly easy do a squeeze-bore as well. Some real interesting options there.

  • therealgreenplease

    Very very cool. I love seeing stuff like this! I’d be curious to see him make a pistol barrel for something like a single-shot 9mm just to see how well the barrel performs.

  • Moonman45

    if the bucket was bigger, and the jig was as long as the tubing was, could you rifle it all at once?

    • Bull

      You could use a pvc tube plugged at the end.

    • JeffreyRodriguez

      It’s worth noting that I’m working from undersize tubing, rather than gun-drilled round bar stock. There’s another 3D guy who’s working on drilling with ECM, but that’s still a work-in progress.

      It’s important to know that ECM preferentially removes the closest material – so the lands will erode and smooth out if I go back to the boring electrode after rifling. I kinda like the “rolling hills” look of that rifling. Who knows if it’s any good. For me, there’s 3 main operations. I alternated between them, but a few times around with this and I could probably work up a ‘recipe’.

      1. Bore the undersized tube to near final ID for the lands with a straight aluminum rod. Basically I just need to get the mandrel in there, which is slightly under the bullet diameter.

      2. Rifle to near final ID for the grooves with a wire-wrapped mandrel.

      3. Chamber by hand-and-feel – I reamed the chamber with an improvised ECM tool. *seemed* to work, still need to test the .44 mag barrel.

      Longer story for the chamber: Some stuck-on ECM gunk prevented erosion at part of the chamber wall, so I had a big ugly steel zit in the chamber. I had to ECM that away by hand, which was a bit tedious, but ideally would be avoided in the first place.

  • FYI: ECM rifling has been in use by the gun industry for decades. However, it is neat to see a homebrew variant.

    • JeffreyRodriguez

      We discovered that S&W has been doing this for their revolver line – some time after playing with it.

      That smooth land-groove transition is a dead give away.

      • In addition, Nowlin Custom and Briley have been offering aftermarket M1911 barrels with ECM rifling since the 1990s.

    • Steel

      Does it last as long as hammer forged rifling??

  • RetroG

    Cool, now you can make what I always considered the hardest part of a firearm at home.

  • Xanderbach

    I used this method to “engrave” egyptian markings on my AK. Awesome to see you can use it for rifling too.

  • int19h

    So, can this be applied to tube barrel as used in e.g. Luty’s homemade SMG?

    • Joshua

      it could, provided you don’t cut the rifling so deep as to weaken the tube to the point where it splits.

    • Wow!

      Most luty builds are rifled. People just use a barrel blank and turn it down for their trunnion instead of the seamless tube he suggests.

      You cannot rifle the tube that Luty specified for 9mm because the bore is already wider than the riflings land diameter. You would have to get tube that is 5 thou or more undersized and or ream out a much smaller tube. Alternatively you can solder in a barrel liner before you do the chambering.

  • Pod

    This is great. I didn’t know the firearms industry used a big-boy version of this to do rifling. Learn something new every day I guess.

    The big part is, as mentioned below, is that this is a home-brew version of the ECM process. Which means that DIY 3D guns will now be more accurate and reliable. You can’t stop technical progress, and you can’t stop the signal. Defdist, FOSSCAD, and more – “how’s that national conversation going?”

  • Tassiebush

    Thanks for sharing all these links

  • Mike Lashewitz

    Wow! I AM IMPRESSED! Very SMART and garage capable!

  • Marco Antonio Gonzalez
  • USMC03Vet

    Time to outlaw electricity and water otherwise ghost guns!

  • James Kelly

    When some unlucky fellow tries to use such a tube for a rifle barrel he may learn that Seamless Tubing is NOT always seamless. Great way to destroy flesh.

    • Wow!

      Generally home gunsmiths use engineering to compensate for metallurgy. For example the trunnions that we make are generally far bulkier than a factory turnnion which is usually lightened. I’ve used all kinds of improper metals and tried to blow it up and I have come to the conclusion that if it is made thick enough in the chamber area it will work.

      Plus most people are making subcaliber guns and not rifles where the pressure drops off quickly down the length of the barrel due to the fast burning powder.

  • James Kelly

    I just posted before reading all the other comments.
    Really, using tubing for a gun barrel is an absolutely deadly thing to do. Whether it is mild steel, like 1018, or a special high nickel alloy any tube can, and a number of them do, have serious long seams in them. If so, one may loose fingers, hands, eyes &c playing gunsmith.
    Been working as a metallurgist since 1963, have both personal and work experience with “seamless” tubing.

  • Ryfyle

    Now there should be no excuses for Favela SMG’s not to be rifled.

  • Wow!

    As cool as this looks, it is a very inefficient method of rifling unless you are doing multiple units simultaneously and in many batches. Mainly because you need more tooling for each diameter and twist rate, but also because you run into issues if you try to rifle a long barrel blank vs multiple short ones. Although having never dove into this aside from reading some industry articles on it and from the experiences of a guy who posted on homegunsmith forums, I can’t say if this issue can or has been corrected for. To me personally, if you are going to make your own barrels just make your own rifling machine. You will have to make a boring machine anyways unless you buy seamless tubing. Mind as well make the machine do both tasks with just a change of the tooling.

    • JeffreyRodriguez

      You’re right about the tooling, caliber+twist+length combination needs it’s own rifling mandrel. Mitigating factors: those electrodes are fairly cheap and easy to make, maybe $15 for 6″ and $25 for 16″ if I were to sell them. Further, ECM causes no tool wear.

      We’ll eventually get this process to bore round stock, in the meantime, I’ve been boring undersize tubing.

      The ECM ‘machine’ fits in a bucket, which I think is a real nice perk 🙂

      Thanks for the input!

      • Wow!

        Again, I have no experience with this rifling technique, I have just read a couple people’s experiences of it on various forums and some starter articles.

        From what you said, I assume that barrel length is no longer an issue as far as the rifling? Compared to a sine bar and a clinton westwood style rifling machines I made, your method is certainly faster for production but my only issue was the limitation of barrel length. Boring round stock with this method certainly interests me. If you can figure that out you certainly will revolutionize how us home gunsmiths make barrels completely.

        • JeffreyRodriguez

          I’ve only been at it since xmas 😉

          I did a rifle-length 12ga test, not with anything smaller yet though. That said, some decent water pressure should allow one to rifle a 16-24″ barrel assuming you have the mandrel. I printed 3 8″ segments and glued them together.

          ECM drilling is a work-in progress, but me and another guy are very interested in making it happen.

          I plan to do just that 🙂 Thanks and stay tuned!

  • Ryfyle

    Can’t wait to see how well this process can be used to ream out barrels. granted you might wanna go and temper and/or heat treat your barrels. Now no one has any excuse for going smooth bore on a Luty SMG. Also might open a huge door for potential home maching on the cheap.

  • James Kelly

    WoW! Whatever grade of steel you choose, whether alloy steel or plain carbon steel, some seamless tubing in that steel will have seams in it. It is likely to burst even with a pistol cartridge. This may remove important body parts of your body.
    Seriously, don ‘t use so-called “seamless” tubing.