Which M203 grenade launcher round is designed to inflict personnel casualties using an air burst effect?

The M397 high explosive jump up fragmentation round is specifically engineered to inflict personnel casualties through an air burst effect. This design is significant because it allows the round to detonate at a predetermined altitude above the ground, increasing the effectiveness of the fragmentation over a wider area. The airburst capability is essential for maximizing casualties, as it disperses shrapnel over a large radius, which can effectively target enemy personnel who are taking cover or positioned in open areas.

In contrast, other rounds like the M394 high explosive focus on direct impacts and ground detonation, which restricts the dispersion of fragments. The M651 chemical smoke round serves a different purpose entirely, primarily providing a smoke screen for obscuring vision rather than causing casualties. The M583A1 parachute round is utilized for delivering pyrotechnics or other equipment with a delay, rather than for direct combat engagement. Thus, the M397 is unmatched in the context of achieving maximum lethality against personnel in combat scenarios due to its unique air burst feature.