MS9557C, MILITARY STANDARD: BOLT, MACHINE-DOUBLE HEXAGON EXTENDED WASHER HEAD, CORROSION AND HEAT RESISTANT STEEL, .250-28 UNJF-3A (06 NOV 1986) [SUPERSEDED BY SAE-AS9557].
MS9557C, MILITARY STANDARD: BOLT, MACHINE-DOUBLE HEXAGON EXTENDED WASHER HEAD, CORROSION AND HEAT RESISTANT STEEL, .250-28 UNJF-3A (06 NOV 1986) [SUPERSEDED BY SAE-AS9557].