Use this stock if you have a shorty M1A similar to a SOCOM or Scout Squad design Along with the shorter barrel. This stock is made from a proprietary carbon fiber composite that makes the stock sturdy but light-weight. The magwell is relieved of material so magazine variations are rapid. https://rivergrzkr.theobloggers.com/35629019/the-fact-about-mk14-ebr-stock-that-no-one-is-suggesting