A Vietnam War Era inert M31 fin-stabilized practice rifle grenade in good condition overall. This example retains much of its original blue pain and has a small dent (pictured). Overall condition is graded at good. The words "GRENADE RIFLE PRACTICE M31 (INERT)" can be seen very clearly on the side. The fin-stabilizers are in very good condition overall. The size is embossed "Loaded 10-63". The Vietnam War-era M31 Practice Rifle Grenade is an inert, fin-stabilized training version of the M31 HEAT (High Explosive Anti-Tank) anti-armor grenade. Used extensively during the Cold War and Vietnam, it was fired from the M1 Garand and M14 rifle using an M7 grenade launcher attachment and special blank cartridges.