The Trinity Force lower bench block can be used to secure an AR15 to a bench vise using the magazine well. This bench block is not intended for weapon modifications requiring high torque like barrel nut installation. For your safety, Trinity Force recommends all weapon repairs and modifications be performed by a qualified gunsmith/installer with an understanding of the weapon platform that the part is being installed on. Always make sure the firearm is unloaded and pointed in a safe direction when working.