| M31 HEAT rifle grenade | |
|---|---|
 Cutaway of M31 HEAT rifle grenade | |
| Type | Anti-armor rifle grenade |
| Place of origin | United States |
| Service history | |
| Wars | Cold War |
| Production history | |
| Designed | late 1950s |
| Produced | 1950s–1970s |
| Specifications | |
| Mass | 709 g (25.0 oz) |
| Length | 430 mm (17 in) |
| Diameter | 66 mm (2.6 in) warhead |
| Effective firing range | 115 m (126 yd) |
| Maximum firing range | 185 m (202 yd) |
| Filling | Composition B |
| Filling weight | 294 g (10.4 oz) |
Detonation mechanism | Nose-initiated, base-detonated |
The M31 HEAT is a fin-stabilized anti-tank rifle grenade designed in the late 1950s to replace the Belgian ENERGA rifle grenade which was adopted by the US Army and US Marines as an emergency stop-gap measure during the Korean War. Like the ENERGA, it has a nose-initiated, based-detonated HEAT warhead, but unlike the ENERGA, the mechanical impact fuse system is replaced with a less complex and more reliable piezo-electric fuse system which also allows higher angles of impact, up to 65 degrees.