Is this Mil Spec or Commercial? — 1 Answer

The question is moot. The distinction between milspec and commercial is in the outside diameter of the receiver extension/buffer tube. Because this item employs a proprietary buffer tube specific to the buttstock, there is no "milspec vs. commercial" issue to consider. It maintains the inside diameter of all ar 15 buffer tubes, and will accept any standard diameter buffer and spring. It should be noted that the tremendous strength of this stock assembly is partly derived from the greater wall thickness of the tube, as well as of the castle nut. One needs to either slightly modify an m4 stock wrench, or use a more traditional pin or hook spanner, with a single point of engagement, to crank down the nut. That said, the threads are milspec and will fit any milspec ar15 lower receiver.