Grenade, DUMMY, M67 INERT with hollow cast iron body and expended striker assembly. The M67 grenade is a fragmentation hand grenade used by the United States military. The M67 is a further development of the M33 grenade, itself a replacement for the M26-series grenades used during the Korean and Vietnam Wars, and the older Mk 2 "pineapple" grenade used since World War II. The M67 hand grenade has an effective casualty radius of about 5 metres.