When fired, the expanding gases generated by the cartridges propelled the grenade forward with considerable force.When the United States entered World War II at the end of 1941, all infantry were issued with the Mk 2 fragmentation hand grenade.[2] The M7 grenade launcher was a tube-shaped device with an overall length (including the mounting bracket) of 7.5 inches.Using markings engraved onto the device to determine the desired range, the rifle grenade was slipped over the launcher.A spirit level allowed the user to figure out the arc of the weapon to aid in aiming the grenade.
M15 auxiliary sight on the left side an M1 Garand.