US Military required grease for AR-15 barrel nut installation. AeroShell Grease 64 (formerly AeroShell 33MS) is an EP airframe grease based on the proven lithium thickener technology of AeroShell Grease 33. For firearms use, it is most commonly used by the US Military for attachment of the M4/M16 barrel nut, acting as an anti-sieze. Simply use a small amount of grease to the upper receiver threads and install the barrel nut to the proper torque setting. AeroShell Grease 64 comprises AeroShell Grease 33 foritified with 5% molybdenum disulfide. It possesses the enhanced anti-wear and anti-corrosion properties of AeroShell Grease 33 with the added extreme pressure properties provid Mfg: Brownells