User:Jackehammond/sandboxes-M31HEAT

M31 HEAT rifle grenade
M31 HEAT rifle grenade fitted to M14 rifle
Type	Antitank Rifle Grenade
Place of origin	United States
Service history
Wars	Cold War
Production history
Designed	mid 1950s
Produced	1950s - 1960s
Specifications
Mass	709 g
Length	430 mm
Diameter	56mm/warhead
Effective firing range	115 meters/effective
Maximum firing range	185 meters/maximum
Filling	Comp B
Filling weight	254 g
Detonation mechanism	nose-initiated, base-detonated

Cutaway of M31 HEAT rifle grenade

External images
Drawings and Cutaways of M31 HEAT
Dimensions drawing of M31 HEAT rifle grenade
Dimensions drawing of M31 HEAT rifle grenade

The M31 HEAT is a rifle grenade designed in the mid 1950s to replace the Belgium ENERGA rifle grenade which was adopted by the US Army and US Marines as an emergency measure stop-gap measure during the Korean War. Like the ENGERA it has a nose-initated, based-detonated HEAT warhead, but unlike the ENGERA, the mechanical impact fuse system is replaced with a less complex and more reliable piezo-electric fuze system which also allows higher angles of impact up to 65 degrees. On impact the nose cover collapses crushing a crystal like material, which sends an electric current through a sepeate wire to the warhead's detonator located in the base of the warhead. A mechanical safety, comprising a set back system located in the warhead's base grounds the firing circuit and prevents the accidental explosion of the warhead. On firing, the sudden launch acceleration, causes the set back to rotate 90 degrees, removing the grounding and completing a firing circuit for the current to flow from the nose to base detonator. And while compared to the ENERGA, the M31 is slightly lighter in weight and has a smaller diameter warhead, the penetration of both rifle grenades are approximately the same armour due to the M31 having a super quick fuse system, plus and a longer nose section resulting in twice the stand-off for the warhead on impact.

The M31 was designed first to be fired from the US M1 and later the M14 rifle. To launch the M31 HEAT a detachable M76 grenade launcher assembly is fitted to the muzzle of the rifle. A M3 ballistic cartridge (two are supplied with each grenade and are crimped to indicate they are only for launching rifle grenades) is loaded into the rifles chamber. The hollow tail unit of the rifle grenade is fitted over the grenade launcher. Official military manuals recommend that the M31 HEAT be fired from either the standing or kneeling position and that it is only accurate against armoured vehicles if fired at extremely close ranges. And while stated to be effective against both heavy tanks (except frontal engagements) and light armoured vehicles when first introduced, by the late 1960s the US Army stated that the M31 HEAT was only effective against light tanks and thin-skinned vehicles.

Various US military manuals issued in 1972, still had sections on the M31, but by the end of the Vietnam War, both the US Army and US Marines had for all practical purposes phased out muzzle launched rifle grenades for the M72 Law rocket in the antiarmour role and the M203 grenade launcher that fitted below the infantryman's assault rifle.

References

• FM 23-3 Tactics, Techniques and Concept of Armor Warfare, published US Army August 1972

• Jane's Infantry Weapon's System page 452, Watts Publishing ISNB 531 03255 8

Category:Anti-tank grenades Category:Infantry weapons of the Cold War Category:Rifle grenades