A stock for a small arms weapon which may include a proximal end surface and a distal end surface, the distal end surface including a first opening extending toward the proximal end surface. The stock further may include a multi-lobe chamber connected to the first opening. The multi-lobe chamber may include a primary lobe for housing a receiver extension. The primary lobe may include a track for supporting a bottom surface of a receiver extension. The primary lobe further may include a first side lobe adjacent to the first wall, and a second side lobe adjacent to the second wall. A first insert may be disposed in the first side lobe and a second insert may be disposed in the second side lobe for isolating movement between the stock and a receiver extension disposed in the track.