Ar-15/M16 Mil-Spec Buffer Tube - Mil-Spec Receiver Extension

Receiver extension tube has the correct, 1.146" outside diameter for mounting collapsible buttstocks designed for the smaller, mil-spec tube. Lets you mount a mil-spec stock on a civilian carbine or convert a rifle with A2-style fixed buttstock to collapsible configuration; carbine action spring and buffer assembly required. Allows fast, easy repeatability of buttstock position with five notches on underside to accept the stock's locking pin and corresponding white position numbers on top visibl