New Gen 2 KAK Super Sig Pistol Buffer Tube

KAK Industries of California has released its latest generation of its pistol buffer tube designed specifically for the Sig Arm Brace. Principal improvement over Gen I is the machined hard-stop on the tube that keeps the brace from moving and allows for the use of the original AR-15 castle nut and receiver end plate.



KAK has machined it to the Sig Arm Brace internal diameter to keep the brace from moving under fire. The tube weighs in at 6.2 ozs and is military-spec hard anodized. For those with longer arms (or looking for longer Length-of-Pull, KAK also has spacers available that fit on the tube. The Gen 2 tube is available for $38 on KAK’s website. The spacers are also in-stock and priced at $12.


Photo courtesy of showing the Gen 1 brace with spacers.

Photo courtesy of showing the Gen 1 brace with spacers.

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.


  • DiverEngrSL17K

    The KAK tube appears to be a well-made and practical device. The stop and LOP spacers, and the ability to retain the castle nut would make it a lot more versatile than other similar tubes. The price seems pretty reasonable, too.

  • echelon

    It is a great product. My setup looks similar to the one pictured and it works great.

  • G

    Why not make it collapsable?

    • echelon

      It’s a pistol buffer with an arm brace.

    • Geodkyt

      THAT would legally be a “stock” – which would make the pistol a “Short Barrelled Rifle” that has to be registered under the NFA.

      As an arm brace, it’s perfectly legal, even if (mis)used by bracing it against your shoulder.

  • Damon

    I am running a first gen and 2nd gen. I was on the fence about sending in my tax stamp. This tube has officially made that a mute point. the only thing left to do now is throw a law folder on it.

    • Tom

      I think the correct term would be “moot” though I do guess in certain applications keeping “mute” about the point wouldn’t hurt.

  • hami

    These tubes allow for an OAL greater than 26″ with a 10.5″ barrel. Because of this, i can use a VFG

    • echelon

      Yes it technically turns a “pistol” into a “firearm” under BATFE classification. Mine is on an 11.5″.

      I find this to be a great article on the subject.

      • mig1nc

        Did you have to use a spacer to get it up to >26″?

        • Synyster06Gates

          OAL is measured from the end of the buffer tube to the end of the barrel or permanently attached muzzle device. Using spacers wouldn’t add to OAL. It is greater than 26” with the tube and barrel alone

          • mig1nc

            Good point. Neither the spacers nor the brace itself are permanently attached so they can’t be counted towards overall length. I don’t know why that didn’t occur to me earlier.

  • Jake W

    You know what’s REALLY fun?

    Putting one of these suckers on an AK and making it fold.

  • kurt

    the “gen 2” mentioned and shown at the top of the article is actually called the SUPER SIG TUBE… not be confused with the original kak “gen 2” tube that is a stand alone tube with the unique peanut fluting..

  • EvanZ

    Yea… KAK is located in Missouri not Cali. Might wanna watch that stuff before you post it.

  • big daddy

    They work great with the SB15.

  • anon

    “kak” means “shit” in Dutch Dialect languages 😀