A 2″ Barreled AR-15 SBR (No, Really)

There are some who say that the AR-15 and its direct impingement gas system is poorly suited to shorter barrel lengths. High Caliber Conversions, LLC laughs in the face of those people:

Some interesting things to note about this extreme(ly silly) SBR AR-15. First, the barrel has been cut down so far that a section of the gas block actually extends past it (it has to to anchor the gas tube with a roll pin). Second, the barrel is in fact shorter than the ammunition it is firing. 5.56mm has an overall length of 2.26″, and with a 2″ barrel nearly a quarter inch of the projectile is sticking out of the muzzle. This means the barrel has virtually no rifling length, and the projectiles start already exposed past the crown of the barrel; in the video the tips of the bullets can in fact be seen before each round is fired.

Third, the extremely short barrel means a large amount of wasted, unburnt propellant. This can actually be seen in the form of black smoke escaping from the ejection port during firing, and in certain frames coming out past the muzzle. It’s likely that due to a lack of significant engraving of the bullet in the rifling, much or even most of the propellant is not being burnt at all, resulting in fairly low muzzle flash, noise, and more modest recoil than one would expect with such an extremely short barrel. In some frames bright flash is evident, but it’s not clear how this would compare with that of other, longer-barreled SBRs.

An interesting but wholly impractical experiment in extremity, to be sure.

Thanks to Retiv for the tip.

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 nathaniel.f@staff.thefirearmblog.com.


  • Jack Morris

    So ballistically speaking, did they just turn an AR-15 into a pellet gun? I can’t imagine the bullet is moving any faster than 300fps

    • Budogunner

      Well, .22lr is scarce. Maybe they wanted a 5.56 NATO trainer for their .22lr upper.

      • M.M.D.C.

        The full-circle shorty is born.

      • Nergyl

        You, sir, have just given me the hiccups from laughing too hard.

  • why


    • floppyscience

      Why not?


        Just because you can does not mean you should.

        • wetcorps

          Just because you shouldn’t doesn’t mean you won’t anyway. Everything doesn’t mean to be serious and practical.

          • MAUSERMAN

            Now I know why “jackass” movie is so popular.

        • floppyscience

          Just because being able to doesn’t mean you should doesn’t mean you shouldn’t.

        • Grindstone50k

          Just because you don’t want to doesn’t mean he shouldn’t.

          • MAUSERMAN

            Ah yes, the motto of every hillbilly mall ninja.

    • Bullphrog855

      How I feel about most SBRs, at least this one is interesting.

  • karm42yn

    Welp, that’s my limit of stupid for the day. Good night.

    • superflex

      Does it go pew pew pew when you squeeze the trigger.
      How cute.

    • noob

      there’s a lorena bobbitt joke in here somewhere

    • JumpIf NotZero

      Agreed. Im confused as to who they are “laughing in faces of” when they are clearly the joke here.

  • USMC03Vet

    I can’t even…

  • quattro

    Love it! Can you make it in a piston version?

  • Mister Thomas

    It’s hard for me to see a “barrel” whatsoever – just a chamber.

    • Budogunner

      I’m not a lawyer, etc. but if I’m not mistaken the ATF measures barrel length by running a rod from the muzzle to the breachface. If this is true, the chamber is included in the measurement so, in a very real sense, you pretty much are just seeing chamber here.

      If anyone can confirm the veracity of the measuring technique with a link to some official source that would be much appreciated.

      • I believe that’s how they do it. Note that the chamber is shorter than 2″, however:


        • Budogunner

          Yep, based on the COAL min/max spec. What we see of the protruding projectile makes sense. Thanks for the link, that seems to confirm it.

          • Yeah, if it has rifling at all it’s only at the very beginning of the throat.

            For all intents and purposes, it’s unrifled. 🙂

      • Phillip Cooper

        That’s pretty much it…

        unless they can come up with another method, which will actually make a given weapon qualify as an illegal SBR. Then, yeah- you’re screwed.

    • USMC03Vet

      It’s only a matter of time until .30 clipazines caliber no barrel ghost guns are targeted by politicians.

    • Wetcoaster

      Is it a short barreled rifle when we can neither see barrel, nor rifling? It looks like it’s all chamber to me too

  • Mike

    Might as well get a shotgun since this is gonna spray bullets all over the place.

    • JK

      Or an AK

  • Patrick R.

    Is this class 3?

    • Budogunner

      The article says SBR, so I assume it is a class III item. They could easily have done this with a pistol, though, and avoided NFA entanglements.

      • Dave Dulin

        Can’t have a stock on a pistol though, and shouldering a brace nullifies it’s intended use and becomes a stock when it touches your shoulder.

        • Budogunner

          Yes, as I said, it has been identified as an SBR. I was just pointing out that this proof of concept coins have been built with less fuss if they simply used a pistol lower. That includes avoiding any activity that would run afoul of ATF decisions.

        • Blake

          Someone needs to catch up on their ATF announcements.

        • Grindstone50k

          WTF did I just watch?

          • A dude from Reddit with not enough to do, I guess. 🙂

            Othais actually invited me on after they stopped streaming. Omnifox was very apologetic then.

          • Grindstone50k

            There’s a few reasons I quit reddit. This sort of thing among them. Oh, yeah. I had well over 100k karma. Tip your fedora before my majesty.

          • JB

            You will never find a more retched hive of scum and villainy than /r/guns. Come back and sub /r/firearms, it’s the saner sub.

          • Grindstone50k

            How about “no” to the whole reddit thing.

        • Gold: 1:30:25
          “I do want to say the only thing that super pissed me off was Alex”.
          I did not intend to anger this man, but rather deescalate the situation in the comments. Whatever, I am sure he is a good man and I suppose apologies are in order if I did indeed upset him.

          • You know, Alex… I’d never actually watched that far. It’s a little sad that he said I don’t actually write articles (i.e., that I’m just an aggregator). People open their mouths before they know what they’re talking about, and they really shouldn’t.

            All because I used some terminology he didn’t like.

    • Somewhere, Omnifox just got mad and he doesn’t know why.

      • Patrick R.


    • Cymond

      Nitpick: class 3 refers to a class of FFL that deals in Title II firearms (like SBRs, suppressors, etc).
      But yes, this is a Title II firearm.

      • Class 3 actually refers to the Special Occupation Tax category that an 01 FFL can apply for. 07 FFLs apply for a Class 2 SOT. Both deal in Title II firearms.

      • Patrick R.

        Is that a yes or a no?

  • Patrick M.

    I believe the medical terminology is “Micro-barrel”

  • 1leggeddog

    So it’s not an SBR.. it’s just an… SR?

    • Dan

      Maybe a NBR (No barrel Rifle)

    • Grendel Medlord

      If it doesn’t have any rifling left, it might be an SBM: Short Barreled Musket.

    • Wetcoaster

      SAC – Semi-Auto Chamber

  • Joshua

    Keyholes…keyholes everywhere

  • Dustin M.

    My only question is “Why?” It just seems utterly ridiculous.

    • M.M.D.C.

      You’ve just answered you own question! Because it’s utterly ridiculous.

      • Dustin M.

        I suppose if you just had money to blow to do ridiculous things, but even then I don’t think I would actually want to have a 2 inch barrel on my AR-15.

  • Vhyrus

    The only thing I can think right now is “Someone paid $200 and waited a year to make that.” Then my mind goes blank and everything dissolves into a red mist.

    • Porty1119

      Nah, they probably have more reasonable uppers to slap on a single NFA lower.

    • Scott C.

      Most likely done on an already registered lower, any other upper is just plug & play. It is a waste though.

  • smartacus

    that barrel would have like 4% longer rifling if it were chambered in .223 inatead of 5.56

  • Ripley

    They should put rifling right into the brass necks.

  • Bobing

    I can’t believe this cycles properly.

  • Mystick

    It’s probably been said, but…. WHY?!?

  • john paul

    I only want one if I can get it in 300blk subsonic.

  • Spencer W

    Well,…..it has a very effective loaded chamber indicator……..

    • ShiningKnight


  • DIR911911 .

    surprised that more aren’t commenting about the fact the bullet actually extends past the “barrel” . . . look close

  • Uncle Webkins

    Clean it up, bro.

  • PT McCain

    What possibly could go wrong with this?

  • Giolli Joker

    What could possibly go wrong?

  • Tassiebush

    That happens to me when I swim in cold water…

  • Superduper tac-shit

    Great, since there’s no barrel , we need nothing to convert it in .300 BLK.

  • Phillip Cooper

    “Hey ya’ll, watch this!”

  • Goody

    Opposite compensating

  • Martin Grønsdal

    arent sights on this thing slightly superfluous?

  • TheNotoriousIUD

    Perfect for CQB drills in your daughters playhouse.

  • HenryV

    I look forward to their bullpup………

  • nova3930

    Gas port is sized at 0.5 in order to get it to cycle….

  • Grindstone50k

    Everyone here getting all butthurt and this guy is having fun. Whose the winner here? I’d say that guy is.

  • TJbrena

    Gentlemen, I believe we’ve found the Modular Handgun System winner.

  • TheSmellofNapalm

    C-clamp THAT, Costa

  • livingonenergydrinks

    All it needs now is a folding stock, and a fire selector switch and you have the american version of the UZI. I am now waiting for someone to try this to an AK47

  • livingonenergydrinks

    I am disappointed they didn’t share what size group they achieved at X yards.

  • Kilo Sierra

    I would be interested how much velocity the bullet can get without a barrel. I guess it won’t travel more than a few yards?!

  • HH

    Looks like Big Sandy shoot to me. Oh and where’s the full auto fire outta that sucker?

  • Eric X Ericx

    Does it come with a Nomex glove?

  • iksnilol

    I kinda want one.

    You could make it somewhat practical if you made the barrel a bit longer (maybe 4 inch?) and made a cartridge suited for such a short barrel. I was thinking 5.56 with the neck blown out to match the width of the case. Then load that with the heaviest bullet you have over the fastest powder you have… or just convert the whole thing to 9×19 or something.

    Bonus points if you use an upper that doesn’t require the buffer tube. Then you could have an actual AR pistol.

  • Duane Oberlies

    good way to loose a finger.