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

The M397 high explosive jump-up fragmentation round is specifically designed for air burst effects, which increases its lethality against personnel. When fired, this round detonates at a predetermined altitude rather than on impact with the ground. This capability allows the fragmentation from the explosion to disperse over a wider area and descend upon potential targets, maximizing the potential to inflict casualties.

In contrast, the other options serve different purposes. The M396 high explosive round is intended for direct impact explosions, while the M651 smoke round is used for obscuring vision and signaling rather than causing harm. The M479 practice round is designed for training purposes and does not include any explosive capabilities. The distinction of the M397 is thus clear, as its design focuses on optimizing casualty production through an aerial detonation mechanism.