A buffer tube for firearms, including assault rifles, carbines, shotguns, and other rifles is disclosed. The floating buffer tube comprises a recoil mitigation mechanism, including a helical spring or an elastic or viscous energy absorption device, and a buttstock mounting bracket mounted outside the buffer tube. The buttstock mounting bracket can rotate relative to the buffer tube, which changes the axial angle of the buttstock relative to the firearm. The angle can be locked under an expansive force by forcing a bolt or pin into grooves to select the proper axial angle of the buttstock relative to the firearm in the field without the user having to disarm himself to perform the angle change.