The carrier is machined from mil-spec 8620 steel, and features a properly torqued and staked, chrome lined, gas key. The Carrier is coated with Nanoweapon for maximum corrosion and wear resistance. The Geissele Stressproof Bolt is made from Carpenter 158, however this is not your typical material spec’d by the US Government. This material is cleaner with less impurities, ultimately making it stronger and more consistent. Using the same process used to produce upper and lower receivers, a forged bolt manipulates the grain structure of the metal and yields a bolt capable of 5 times the life of a mil-spec bolt. Each bolt is then rigorously inspected, high pressure tested, mag particle inspected and coated with Nanoweapon for maximum corrosion and wear resistance.