AR-15 Carbine Buffer Tube

Carbine Buffer Tube

The United Defense AR-15 Carbine Buffer Tube is the receiver extension that screws into the back of an AR-15 lower receiver. It houses the buffer and recoil spring and gives a collapsible stock its rail to slide on. If you are building a lower from scratch or replacing a worn or damaged tube, this is the part your stock mounts to.

Features

• Carbine-Length Receiver Extension — Carbine tubes are the shorter, stepped style made for adjustable stocks, as opposed to the longer fixed-stock rifle tube.
• Six Adjustment Positions — Six detent holes along the underside give a collapsible stock six length-of-pull settings, so you can set the distance from trigger to buttstock to suit your build and your gear.
• Keyed Underside Rail — A flat raised spine runs along the bottom of the tube, holding the stock in line and stopping it from rotating.
• Threaded Front End — Fine external threads let the tube screw directly into the buffer tube threads at the rear of an AR-15 lower receiver.
• Closed Rear Face — The back of the tube is closed off, with a small center hole visible in the end face.
• Matte Black Finish — The even, low-glare black finish matches most AR-15 lowers and stocks.
• Machined Profile — Clean cuts at the detent slot, rail step and threads show careful machining throughout.

Fit and Assembly

The photographs show the tube by itself. A working setup also needs a buffer, buffer spring, receiver end plate and castle nut, the slotted nut that locks the tube in place against the lower. Carbine stocks are made to either mil-spec or commercial tube diameters, so check which standard your stock uses before you order.