Loctite 603 is designed specifically for the bonding of cylindrical fitting parts, particularly where consistently clean surfaces cannot be assured. This retaining compound cures when confined in the absence of air between close fitting metal surfaces and prevent loosening and leakage from shock and vibration. 603 is particularly tolerant of oil and other contaminants. FNH recommends the use of this product on the attachment of its rail systems for the SCAR and 16S/17S rifles.
Big Book Catalog, Issue:67, Page:508