New Bolt Carriers With Integral Gas Keys By Voodoo Innovations

Here’s an idea: Making AR-15 carriers with integrated gas keys. Of course, if you are just milling carriers out of round stock on a horizontal machine as in a military BCGs, then this would considerably increase the amount of material you need to hog away to create a carrier. However, if you are making the carriers from scratch yourself, as manufacturer Voodoo Innovations is, then this may make some sense. From their press release:

VooDoo Innovations’ NEW Integral Bolt Carriers are now available!

Our new Integral D.I. Carrier was designed from conception to improve the service life and durability of the direct impingement carrier. The VDI Integral DI Carrier eliminates the potential for carrier to key separation due to carrier key screws stripping, fracturing, or becoming un-staked. The new Integral carrier has a improved gas flow path with no obstructions or shelves for carbon to deposit and build on eliminating the potential for gas obstruction to seize the operation of your carrier. The 20% reduction in carrier weight in the Low Mass Carrier decreases the reciprocal mass reducing felt recoil and increasing the Tune-ability for every application.


VooDoo Innovations

With a properly staked gas key, the problems the Integral Carrier is designed to solve should happen virtually never. However, I still feel the integrated bolt carrier is pretty slick, and I admit I am tempted to try it on my next rifle build.

Nathaniel F

Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. In addition to contributing to The Firearm Blog, he runs 196,800 Revolutions Per Minute, a blog devoted to modern small arms design and theory. He is also the author of the original web serial Heartblood, which is being updated and edited regularly. He can be reached via email at


  • Giolli Joker

    “Of course, if you are just milling carriers out of round stock on a horizontal machine as in a military BCGs, then this would considerably increase the amount of material you need to hog away to create a carrier. However, if you are making the carriers from scratch yourself, as manufacturer Voodoo Innovations is, then this may make some sense.”

    Sorry but I find it hard to make a sense out of these two sentences.
    What you’re trying to say is that most manufacturers machine their carriers out of round stock on a lathe while VI machines them out of bar/flat stock on a multiple axis CNC machine?
    Therefore they can do everything on one machine instead of moving the part from lathe to another milling machine?
    Either way it’s manufacturing from scratch, by machining, removing material.
    Unless VI produces by investment casting or DMLS… both technologies that I wouldn’t trust much of such a component.

    [On a (even) more pedantic note, just because I see that you usually put more care than others on your wording, the verb “to create” has no place in manufacturing.]

    • RickH

      Yeah, I can’t find out exactly either what the difference is in the manufacture of this item. So what is “making it from scratch”? The link provides no information really.

    • noob

      maybe it’s about the geometry – if you have a flat piece of bar stock barely long wide and tall enough to contain the bcg and gas key, that’s less material to remove than lathing and milling away from round bar stock that has *diameter* enough to hold the bcg and the gas key *and* is centered so you can turn the round bar so the final part is centered around its long axis.

  • Pedro .Persson

    They could be casting, if done properly it will be just as good as a machined part. 3D printing is a no, just too expensive and just not good enough. Frankly I would just weld the thing, or if I truly want the part to be replaceable I would come with some sort of slot to reduce stress on the screws, on pin the screws, or just redesign the key to be just a tube that threads in place. What actually bothers me is the low mass carrier-thing, isn’t the AR-15 already running fast enough to the point were some mags have trouble keeping up? I tought that the consensus for a field gun was to shove the heaviest buffer and carrier possible in the gun and cycle it slowly but still retaining the same energy.

    • Giolli Joker

      Investment casting and MiM are both feasible, but I doubt that the quality required can be obtained with relatively limited production numbers, without astronomical MSRP.
      Anyway, they’re machined, I checked, and I was basically pulling Nathaniel’s leg to have him adopting his academic approach even when he has to talk about manufacturing technologies.
      The reference to DMLS was to pull the leg of those who believe it is a mass prodution process.

      • Pedro .Persson

        Yes machining is useful for this sort of limited run, but once you start getting into some more complex geometries, extreme dimensions, and materials casting in all its forms began to become an attractive solution for both small and large productions. I recall an example of that, Pagani has a decorative element on their engines, a stupid fake heat sink on the intake manifold (made out of CRFP… on a naturally aspirated engine) that they spend three days machining on an outsourced shop, casting that thing would save them so much money and time it makes me cringe, but they can afford this needless expense and brag about it. If someone wants to go fancy with the gas channels of the carrier then it would be prudent to consider casting or welding a cast part. If the process is compatible with the part, it’s function, the size of production run, it’s well executed and has proper heat treatment and surface finish and inspection then the quality and price will be there.

    • raz-0

      You run low mass to reduce reciprocating mass. Unless your gun has other issues like a small gas port or too long a gas system for the barrel length, you need to reduce the gas fed to the gun to get the benefit of a lower mass carrier.

      On a rifle, the carrier and buffer are not outrunning the magazine. With a carbine length gas system, especially on a 16 inch barrel, port pressure goes up a lot and dwell time increases, so you can start getting very fast cycle times. It’s a balancing game of ammunition, carrier weight, buffer weight, buffer spring rate, gas port size, gas port position, and barrel length.

      Most guns come overgassed, I suspect because fixing QC problems is as simple as grab a heavier buffer from parts bin B instead of parts bin A. The love of the m-16 carrier is probably in part due to the magic of the words “mil-spec” and in part due to the gun enthusiast hive mind being filled with part truth and part fantasy but frequently not a lot of details. There were definitely SA only carrier designs out there that were somewhere between bad and dangerous. You have to work to dig one up though.

      Putting in a heavier buffer can help recoil be a bit softer, but the effect when the bolt is returned to battery is greater. This is why on a lot of guns with an effective comp, you get barrel dip. Reduce the carrier mass, buffer mass, and gas supply, and recoil gets a LOT lighter, and the force of returning to battery is decreased as well. Done right, you don’t outrun the mag, and the gun barely moves when you shoot. Go too far and it’s a single shot due to too little gas, the BCG bounces back out of battery, or it likes only very particular ammunition. It might even be picky on a seasonal basis. Like everything there’s the right ammount. The add weight school can wind up with short stroking by moving from slightly overgassed for the mass to slightly undergassed (I’ve seen that a lot with mid length 14.5″ barreled guns where someone slapped in an H2 buffer because the interwebz assured them it was the awesome and ensured reliability. Especially once winter arrives or they start shooting something that isn’t 5.56 pressures because that’s what is cheap and/or available. With a running lightened setup, I have seen it start outrunning the magazine, usually due to gas port erosion over time. Or short stroking once winter comes due to less gas pressure.

      • Pedro .Persson

        Well that sure was interesting, and I should have remembered that the AR-15 platform comes with a lot of variations on the gas system length; thanks for the correction. Perhaps a lot of folks try to emulate the (in comparison) grotesquely overgassed AK family in search for reliability. I probably wouldn’t go too far in the weight reduction, probably would try to strike a balance between recoil and cycle speed to keep just enough energy for reliability in a well kept civilian rifle (see AK comment.) Just a question, spring selection is more of a matter of total energy on the cycling than speed per se, correct?

        • raz-0

          Well spring rate is a matter of maintenance, or gaming the margins. Take a functioning gun set up to work with a wide range of ammo, lose about 10% of the oomf in the spring, and you can see it start getting finicky intermittently.

          Go really light with a lightened buffer and carrier, and increased spring rate over spec can help reduce bolt bounce by exerting a bit more pressure at full extension in the buffer. (note: this last one is my current understanding, I’m just starting to play with seriously lightened systems).

          I think the industry tends towards overgassed because if it is only semi-auto use, the balancing act has more margin and easier fixes if you go that way.

          If I ship a slightly over gassed gun that is out of spec, I can fix it for a customer by shipping them a heavier buffer. If it is undergassed, the simplest/cheapest thing I can do is drill out the gas port on the barrel.

          • Pedro .Persson

            But if you go with too strong of a spring for a given weight you need more gas, maybe getting too fast or not having that much recoil reduction. I can imagine it gets tricky kinda fast once you go extreme. Bolt bounce is not something I fully understand, I imagine it has quite a few factors at play, I recall someone saying speed and mass play a actor too (the vuurwapen guy), then that receiver rigidity is also a factor wen I did some research on the AK-74 and why it has that hammer retarder. And adjustable spring, removable weights for the buffer and carrier, and an adjustable gas block would probably make for a nice set-up.

  • Joshua

    So how exactly did they manage to drill the hole to lead the gas into the expansion chamber, and if this is a MiM product good luck to them……hahaha

    Also the exhaust vents are not the correct size judging by the picture.

  • Giolli Joker

    According to their website its machined.
    Therefore, likely, the blank gets forged, possibly by a supplier, to its rough shape and then machined in house to the final dimensions.
    Good if done right… just hoping they didn’t drop a “drop” before “forged”…