The Armat Battlefield Systems M40 High Explosive Dual Purpose (HEDP) Grenade (also known simply as the M40) is a type of high explosive fragmentation grenade predominantly employed by the United States Colonial Marine Corps.[1]


The M40 is primarily designed to be fired from the U1 Grenade Launcher or other U-type grenade launchers (such as the U4, U4A2 or U4C), although it can also double as a hand grenade. The cartridge consists of two main sections — a rimmed, separating base and a metal casing topped with a red plastic identifying cap. When fired from a U1, the base propels the casing from the grenade launcher's barrel with a muzzle velocity of around 78 m/s.[2] The grenade round has an effective range of 400 m, and an accurate range of around 180 m.[2] The projectile itself contains notched steel wire wrapped around a Composition B15 explosive core, which spreads more than 300 metal fragments over a casualty radius of 5m upon detonation.[2]

Despite its main purpose as a launched projectile, the M40 can be employed as a hand-thrown grenade by flipping off the red plastic cap and depressing the button beneath.[1] This will trigger a three second fuse, after which the round will detonate.


M40 HEDP grenade

Behind the Scenes[]

Atherton shows grenade

Armorer Simon Atherton displays a grenade prop.[3]

The 30mm grenade props seen in Aliens were constructed from 12 gauge aluminum snap caps (an inert cartridge simulator made to the same external dimensions as a live round, used for training purposes); the fact 12 gauge rounds are actually only 18.53 mm in diameter is simply ignored in the film. The snap caps were embellished with additional machining cuts made for cosmetic appearances, a push button on the top, and a colored plastic cap, which was red for the M40 high explosive rounds seen on film.[3]

The Harry Harris Aliens Collection & Archive contains a grenade prop made from turned wood and painted silver. While it is not known if wooden grenades were used during filming, it's possible they were lightweight copies worn by stunt performers.[4]

In Aliens: Colonial Marines, the M40 is unlocked by default, as with the M41A Pulse Rifle MK2, M37A2 Pump Shotgun and M4A3 Service Pistol, this is barring DLC unlocked weapons.


  • In real life, the acronym HEDP is an alternate designation for high explosive anti-tank (HEAT) warheads, which use an explosive shaped charge to penetrate solid vehicle armour. In the case of the M40, the "dual purpose" moniker presumably refers to the fact the grenade can either be launched from a U1 Grenade Launcher or hand thrown.