US Cartridge, 40mm HE, M397A1
This cartridge is a high explosive round designed to inflict personnel casualties using air burst effect, and is fired from 40mm Grenade Launchers M79 and M203 (attached to the M16 series rifle).
This cartridge is a fixed round of ammunition consisting of a one-piece steel projectile body with a metal rotating band and a cartridge case assembly containing the propelling charge and percussion primer. A hollow ogive is fitted to the front end of the projectile. A hollow steel ball assembly containing a delay detonator, a booster charge, and an HE bursting charge, is fitted into the rear end of the projectile. A PD fuze assembly is threaded into the front opening of the ball assembly. The projectile assembly is press-fitted into a cartridge case. The case is a hollow bi chambered aluminum cylinder with an annealed brass propellant cup assembly fitted into the center of the cartridge base.
The cup contains the propelling charge and a percussion primer in the center. The cup acts as a high pressure chamber, and the hollow cavity in the case, which surrounds the cup, acts as a low pressure chamber.
Collaborative Ordnance Data Repository