US-8800189-B2

The present invention is a buffer tube assembly 2 upon which stock modules may be mounted as part of a modular stock system. The best mode buffer tube features a uniform cheek plate 10 with a track 9 disposed underneath the cheek plate 10 on either side. Rail track 8 is disposed on the underside of buffer tube module 2 and is divided in half by a longitudinal groove. Interface detents 5 are provided on the sides of buffer tube module 2. Both rail track 8 and detents 5 are provided for interface with adjustable length stock modules. Individual half-rails of the rail track 8 may be angled to improve interface performance with adjustable for length stock modules. A clip hole 13 is provided as a securement means with fixed length stock modules. The invention may also be practiced as a mounting assembly for those firearms (usually air projection type) that do not require a buffer area.