Thorsden Customs’ AR Pistol Buffer Tube

For those in restrictive states, Thorsden Customs may be a very familiar name. Thorsden is the shop that created the one of the first compliant non-pistol grip AR stocks that now typify NY and some CA-compliant rifles. Further expanding their compliant products is the AR Pistol Builder’s Package, which adds storage and a better cheek weld to the buffer tube for AR pistols.

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Thorsden describes their system best:

Our QD buffer tube cover mounts over our exclusive keyed buffer tube and provides a rock solid base for the CAA saddle. The cover also incorporates one quick detach sling hardpoint on each side. The CAA saddle provides a positive and stable cheek weld, as well as, handy storage for batteries, tools, or other items. Our new adapter merges the two perfectly using all of the original hardware from both kits, eliminating the use of glue, tape, or zip ties to attach the saddle to a standard pistol tube.

LIke Sig, Thorsden Custom has the ATF determination letters publicly available on the system. The BATFE has determined that the storage system as configured does not substantially alter the buffer tube and turn it into a shoulder-able stock (despite significantly increasing the rear surface area).

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The full AR Pistol Builder’s Kit is available direct from Thorsden Customs for $117.99 and is available in OD, FDE, and Black. The kit includes one each of the following:

  • Keyed Pistol Buffer Tube (Thordsen Customs exclusive)
  • QD Buffer Tube Cover (Thordsen Customs exclusive)
  • Saddle Adapter (Thordsen Customs exclusive)
  • CAA Saddle kit
  • Carbine Buffer spring
  • 3.0 oz. standard recoil buffer
  • Castle Nut
  • Mounting hardware
  • Endplate
  • Installation instructions

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Nathan S

One of TFB’s resident Jarheads, Nathan now works within the firearms industry. A consecutive Marine rifle and pistol expert, he enjoys local 3-gun, NFA, gunsmithing, MSR’s, & high-speed gear. Nathan has traveled to over 30 countries working with US DoD & foreign MoDs.

The above post is my opinion and does not reflect the views of any company or organization.


  • casey

    Magpul needs to release one of these similar to the top half of their UBR stock

  • sianmink

    That’s pretty sweet, but my dream AR pistol would have a folding stoc…er, arm brace and piston system for maximum stowability.

  • big daddy

    I really like the KAK tube and SB15 brace. I don’t think it’s sturdy enough for anything more than a fun gun or HD. If it can do what the brace does in terms of firing the gun in a way not meant with the SB15 I would be interested. So it has to be comfortable shouldered. I tried a phase 5 tube with a command??? I think it was, saddle and it was NOT as comfortable as the KAK/SB15 combination. So I wonder how good this is, but I see some differences, it’s worth a try. It’s all about LOP if you use it in that way.

    • Cymond

      Yeah, I put a CAA saddle on a pistol tube a few years ago, it really wasn’t very good but I think it was an improvement over a simple foam cover. At least I liked the cheek weld with the CAA saddle, but that was back then. The SB-15 is probably the single best AR pistol accessory on the market now.
      I’m about to move from CA to SC, so I recently bought a KAK tube. The KAK will wear the CAA saddle until I get around to buying a SB-15. (I’m saving my money for a suppressor!)

      • big daddy

        Yeah the SB15 made the AR pistol viable to use accurately. The way my health is going I might end up using it the way it was designed to be used, as a brace.

      • RobGR

        Why not SBR when you move out of CA?

        • Cymond

          I have multiple lowers. Due to the way lowers are transferred in CA, they can only be built into rifles. The only way to get an AR pistol in CA is to buy a complete pistol or make your own receiver (part of the popularity of 80% lowers here).
          Anyway, I do plan to SBR one lower that I bought in CA. However, I also have a virgin lower that I bought before I moved to CA which is still legal to build as a pistol. I like the idea of a pistol with brace for the car, and for travel across state lines. I have friends in GA and family in WV.
          Besides, there’s no legal way to make a SBR before I’ve established residency in SC. An AR pistol can accompany me on the road trip.

    • echelon

      I generally agree with your assessment, but if one is going to be using an AR pistol for anything other than a fun gun or HD, why pray tell would they not just slap a regular tube/stock on it? I’m talking SHTF or WROL scenarios here.

      So for all intents and purposes I believe the KAK tube and SB15 get you 95% of the way to SBR land as far as usability with the added benefit that you don’t have to report when it crosses state lines, etc.

      • big daddy

        For SHTF my worries are not gun related, I’m more worried about getting the medications that keep me alive. I live in Texas now and I will never ever leave. I’m originally from New York City, no way will I ever go back or even think of leaving the great state of TEXAS!!! or should I say country of Texas…..:-).
        For anything gun related I have a very nice DDM4V5 and a M&P 9mm both with the right ammo to do the job and plenty of it.

        • echelon

          Agreed, but I’m just saying that in a SHTF or WROL situation I’m not going to be worried about stupid NFA laws either so there’s no reason not to turn it into a real “SBR”…

          Especially if you live in an urban environment or are bugging out in a vehicle the compact size will be desired.

          So it makes the “it’s a range toy” or “it’s not for serious use” arguments moot for me personally.

          • Cymond

            My one concern would be that in a bad situation (SHTF, WROL, whatever), law enforcement may still be present in some small numbers. Although looting and chaos was widespread after Katrina, I also read cases of law enforcement disarming decent people. If something like that happened, I wouldn’t want to be facing NFA charges afterwards.
            Of course, in an absolute SHTF/WROL situation, there would be no LEOs whatsoever.

          • echelon

            All I’ll say is dead men tell no tales.

            In a SHTF/WROL situation anyone who tries to disarm me and take away my right to self defense will be met with extreme prejudice…

      • Brian Flate

        The KAK is even better now that you can but a set of 2 rings for $12 that allows you to add more inches for more LOP if you want……excuse me ….not LOP….but rather a better fit for a really long forearm…. yeah that’s it….long forearms.

  • Zachary marrs

    So is the sig brace “outlawed” in restricted states? It does have storage space, which is neat.

    • Cymond

      It’s not outlawed in any states that I’m aware of but I’m sure a few will find a way to ban it eventually. However, this tube cover was originally an accessory for the FRS-15 stock, which was released back in late 2012, long before the SB-15 came to market.

  • Green Hell

    It gives me really sweet and warm feeling inside, to see how the stupid laws are so beautifully got around.

  • Cymond

    It’s important to remember that the Thordsen Custom tube cover was released with their FRS-15 stock, long before the Sig SB-15 brace came to market. I think the SB-15 is probably the best option for AR-15 pistols on the market right now, but some may still be uncomfortable with it.
    Also, it is factually untrue that ” Thorsden is the shop that created the first compliant non-pistol grip AR stocks”. The groundwork for the FRS-15 stock was the old U-15 stock, but it was produced in very small numbers and was expensive.

  • John Fletcher Kilgour

    Even in Ukraine the SHTF situation is very “local”. Probably that true to a lesser extent in Syria, but nonetheless true in some places. If such a situation happened here, in USA, there’s no reason to think it would be widespread or “nationwide”, but to a limited extent lawlessness would probably be rampant everywhere. What I’m trying to say is that if one had an AR in (for example) Ohio, and there was a rebellion situation in the center of the country, or in the South, etc, there would probably still be enough active LE in Ohio, and enough “stability infrastructure” in Ohio that one could not simply self-declare the NFA “repealed” and turn one’s AR into an unlicensed SBR on the fly. If there’s chaos in Ohio, what makes you think the rule of law would be gone in New Mexico (for example)? People don’t realize how big this country really is. You could have 10 states in chaos and the rest of the country would just yawn and go about their regular lives.

  • valorius

    This gadget makes an ar pistol a hell of a lot more practical and useful.