AR Pistol Revolution


Many have seen the SIG arm brace by now, but have you seen the dedicated pistol buffer tube made for it?

The world of AR-15 pistols took a turn recently when the ATF ruled the addition of a SIG brace to an AR pistol buffer tube does not deem the firearm an SBR. In addition the ATF added that it is not illegal to shoulder the SIG brace when shooting. AR Pistol owners have been rejoicing ever since.

While the SIG brace is an awesome addition to any AR Pistol, the KAK Industry SUPER SIG SB-15 buffer tube made specifically for the SIG brace makes a world of difference for the shooter.

KAK Industry is located in Lees Summit, MO and specializes in the design and manufacturing of wildcat uppers for the LR-308 platform and AR15. I spoke to KAK founder Kurt Kosman’s who shared his roots and passion for making wildcat parts such as barrels and uppers in 358 Winchester, 350-300 WSM, 375-300 WSM, 450 Marlin and 458 SOCOM. “It is our specialty and what we do best”, said Kosman.

Enough about KAK, lets talk about the real reason we are here. The SIG SB-15 pistol buffer tube is a dedicated tube designed to work exclusively with the SIG Brace. The patent pending tube was designed to be a perfect fit for the Sig arm brace and provides a shoulder for the brace to rest up against, giving the shooter a longer length of pull.

The mil-spec anodized tube weighs only 6.2-ounces and is 8.45” long from the end-plate.


Installing the tube was fairly straight forward as it screws directly into the lower receiver just like any AR buffer tube. The tube utilizes a standard carbine buffer and spring just like any mil-spec or commercial buffer tube. Installation took about 15 minutes and was really easy. You will need a castle nut tool to tighten the castle nut.

The Sig brace slid on with a decent amount of pressure required to fit it in place. This is a good thing as you don’t want it walking around while shooting. I was a little concerned that the anti-rotation tab found on the SIG brace no longer locks into the end-pate and that it might cause the brace to move, loosen or rotate when shooting. To date we have put hundreds of rounds down range with this setup and the brace has yet to walk on the tube. That being said, it is still a concern I have. I have not heard anyone complain of walking issues, but I thought I would mention it just in case.

I am enjoying having a dedicated tube for the SIG brace and have since bought a few of KAK’s standard pistol buffer tubes to use on my pistol builds. This is a must have if you are going to run the SIG brace on your AR pistol.

As of this writing, the tube is available as a kit (sig tube, castle nut, QD endplate, buffer and spring) for $93 or as a stand-alone tube for $42. KAK also makes a spacer kit to extend the tube as well as FDE and OD green versions. You can find more information on the buffer tube here.

Stripped Super Tube
Super Tube Non-QD Kit
FDE & OD Super Tube
Tube Extended Spacer

* The views and opinions expressed on this web site are solely those of the original authors and contributors. These views and opinions do not necessarily represent those of Guns & Tactics Magazine,

the administrative staff, and/or any/all contributors to this site.


  1. If I lived in the US I’d be all over this stock and buffer tube. Its these little loopholes that gives us hope as shooters to enjoy more what we love so much. In Canada, where I’m from, has many ridiculous laws, but SBR’s can have stocks here. Because of the laws being what they are, a lot of these laws intertwine and cancel each other out. Good example is magazine capacities. But that’s a whole other conversation.
    To all my American friends, congrats on a victory.


  2. To mention a concern, even though you have determined it is not a concern through shooting the Pistol, is just plain asinine.

    Something to mention and clarify here; “Super” Sig Tube means its a sig tube that can take a castle nut and regular Carbine End Plate. If it doesn’t not have the word “Super” in front of whatever Tube you’re talking about, then it just screws into the receiver just like any A2 Rifle Tube.

    How is a photographer as an author worthy of reviewing operator parts such as the Super Sig Tube? Where are the real shooters at?

    • Chesty P. Thank you for clarifying the two tubes. It was my understanding KAK will not be offering the old design any longer once sold out so I did not mention it. In addition to being a professional photographer, I am also a professional firearms shooter, instructor and have 20+ years working with firearms. Sorry you did not get the memo 🙂

    • IMO the review is well done, on point, and provides information that all AR pistol owners can use when making decisions on which buffer tube to buy.

      Operator? You do realize that real soldiers don’t use such terms, they let their actions speak for them. Only “wannabes” feel the need to attempt to aggrandize themselves is such a manner.

      Since when is a AR buffer tube an “operator” part? Every AR on the planet has one, and there are millions of people that own ARs that don’t wear camo or feel the need to use made up terms like “operator”.

      Do you always ridicule other people in order to make yourself feel better?

  3. My concern lately is that if parts are made for the sig arm brace to make it easier to shoulder then the ATF will retract its statement and the use of said items will make it a SBR. Don’t get me wrong, I’m all for the sig arm brace. We’ve been given a leeway and yes a loophole but let’s not abuse that. Also I don’t consider this “loophole” a privalge. The right to own is a “RIGHT”, via US Constitution. I do plan on owning one in the future and they are a great idea. I just want to give them any reason to strip us of our rights anymore.

    • Rick Littleton, Like you I believe the last thing you ever do is tease a rabid dog. and the BATFE is indeed Rabid. The Logic that a pistol being made bulker and less concealable, should be unlawful is at best, a joke. Any agency that would push such an agenda should Not be trusted.

Comments are closed.