The MK258 Mod 1 APFSDS-T Swimmer round is the most advanced ammunition technology available. It will be effective towards various surface threats, small to medium sized boats, personal watercraft that can be loaded with explosives, and submerged targets, or it can be fired through the waves before impacting the target. The tungsten penetrator provides a short time of flight, high impact energy and maximum penetration capability out to more than 4 000 m.