WMD Guns 5.56mm 6 Positions Carbine Buffer Tube Mil Spec Black. The 6 Position Nib-X is a big hit with the younger crowd who want there guns to look like a 'normal' gun and not a "castle" build. This buffer tube can be used on a standard AR buffer tube pin or a standard AR extended buffer tube pin with a longer overall length. We decided that a more aesthetically pleasing option than a plain ole' steel tube. So after a day at the range with our 6 Position Nib-X Buffer Tube you may want to consider a more refined option. This tube has been extensively machined and anodized for wear resistance and durability. It is easy to install and even easier to remove. Specifications for WMD Guns 5.56mm 6 Positions Carbine Buffer Tube: Manufacturer: WMD Guns Gun Make: AR Platform Gun Type: Rifle Package Contents: WMD Guns 5.56mm 6 Positions Carbine Buffer Tube WMD Guns BT-A: 5.56mm 6 Positions Carbine Buffer Tube Mil Spec Black