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.