By David Higginbotham
KAK Industry, LLC
AR pistols have always seemed a bit odd to me. They’re almost too heavy to be fired as pistols. The odd tube sticking out of the back makes them look unbalanced. Recoil is so jarring that repeat shots are slow. You can fire them as you would a pistol, but why would you? You can get all jammed up on the gun and shoulder the buffer tube, but why? I tried them out. I wanted to believe, but I didn’t get it. Then came Sig Sauer’s Pistol Arm Brace. The brace makes a great improvisational stock, but you really need the right buffer tube between the pistol and the brace to make the most of it. KAK’s Super Sig SB-15 Pistol Buffer Tube insures that the brace-as-improvised-stock (or even as an arm brace) performs exactly as it should, every time.
Sig has just sent us a SIG556 pistol to review. It is a great gun. As a pistol, though, it is almost impossible to shoot accurately. It seems a bit odd to talk about the SIG556 without an arm brace, so we got back in touch with Sig and they sent one for the review. But they didn’t send a buffer tube. As it is almost impossible to attach an arm brace to a SIG556 without a buffer tube (or a lot of duct tape), I went in search of the perfect match. Enter KAK Industry and the Super Sig SB-15 Pistol Buffer Tube.
Before Sig launched its arm braces, its line of rifle-caliber pistols was a popular starting point for those wanting to register short-barreled rifles (SBRs). With a stock attached, the Sig pistols become formidable SBRs. The arm brace began its life as an arm brace, something you attach to a buffer tube that allows you to strap the pistol to your forearm. Yet recent rulings by the ATF indicate that it isn’t illegal to shoulder an arm brace. And now these pistols and braces are flying off the shelves. KAK’s new dedicated tube is perfect for those who want to skip the SBR registration process and get serious about using arm braces on AR pistols.
At first glance, the KAK tube looks like many other buffer tubes. It is round, aluminum and has that flat black finish that defines the AR platform. Yet there are a couple of subtle differences that make the new version stand out. The first is the necked step on the outside of the tube. The arm brace’s tube sleeve is 6.5 inches deep. The KAK tube is necked at that length, which keeps the arm brace from sliding toward the gun as the recoil pushes the tube back in the brace. This makes for an ideal SBR stock. Length of pull isn’t as much of a consideration when you’re trying to keep the whole package compact. Even oversized oafs like me can jam up on a short stock when we have to.
The rear of the Sig arm brace is wide enough to make an effective stock. After shooting more than 500 rounds through the SIG556 for the initial portion of the gun review, I can’t feel any before/after difference in my shoulder. And this brace never moved. It was easy to muscle on and off, yet stayed true during shooting. There was no forward movement and no rotation.
And if you do want some extra length of pull, KAK makes two collars that can be used alone, or together, to add anywhere from .625 to 1.25 to 1.9 inches of extra length. The real appeal of the collars is the extra length, but there is an added benefit: extra give. With the brace and tube mated completely, the end of the tube is flush with the end of the brace. If you do happen to shoulder it oddly (like against your collarbone instead of lower on your chest), that aluminum is going to bite. With the spacers on the tube, there is an equal length of rubber displaced at the end. With both spacers on, there is almost two inches of rubber at the end. While it isn’t even as squishy as some shotgun stocks, it isn’t aluminum. The squishiness combined with the KAK tube’s ability to keep the arm brace from moving makes the perfect combination.
As a control in these experiments, we put the brace on a typical AR pistol buffer tube. The difference was noticeable from the moment of instillation. The brace was much harder to get on the tube. As it is rubber, the brace didn’t tear out, but the fit was tight. And when shooting, the brace crept down the tube, as there were no stop to keep it still.
This is the second generation of the KAK arm brace tube. This one attaches with a typical endplate and castle nut. The endplate they sent us has a QD sling mount, which is the perfect position for a QD sling on an SBR. The endplate also has a tab that mates with the tube to keep it from turning, so there’s no real need for Loctite. If your AR needs the buffer and spring, those are included in the kit. The whole package includes the tube, the buffer and spring, the castle nut and the QD endplate for $93. The extension sleeves are an additional $12. KAK even sells the Sig braces, too. From my perspective, it is an easy choice. Check out KAK.