Munition flies in a pocket in water [CANSEC2016D2]

26 May 2016

Nammo (Booth 1001) is showing a revolutionary 30mm munition designed to engage fast inshore attack craft (FIAC)-type surface threats out to more than 4,000m.

Shown for the first time in Canada, the 30mm x 173 Mk 258 Mod 1 armour piercing, fin stabilised, discarding sabot-tracer (APFSDS-T) ‘Swimmer’ munition is the outcome of a collaborative venture with the US Naval Sea Systems Command Naval Systems Warfare Center (NSWC) in Dahlgren, Virginia, to develop a counter-FIAC capability for amphibious platforms.

Weighing 230g, with a muzzle velocity of 1,430m/s and maximum dispersion of <0.4mils at 1,000m, the novel design of the Mk258 Mod 1 enables precision shooting in air and in water, expanding the lethality of ship-based cannons such as the Mk44.

“We had an idea to modify the front section of the penetrator to make it supercavitating – essentially it will fly in a pocket in the water,” said Jan Hasslid, director of global sales and marketing for military ammunition and shoulder-fired systems at Nammo.

Previous analytical studies of water-penetrating projectiles concluded that a normal spin-stabilised projectile is ineffective at maintaining stability after water entry.

This means immediate stoppage of the projectile and zero impact on a submerged target.

However, the Mk258 Mod 1 projectile is fin-stabilised, based on the same components as the MK258 Mod 0, which was designed for use with the Norwegian Armed Forces CV9030N combat vehicle.

The only modification is the nose shape of the tungsten penetrator, which was patented by the US Navy and NSWC Dahlgren, but never turned into functional ammunition.

“Against a typical FIAC threat travelling at 30kts, the below-water impact is particularly destructive,” Hasslid said. Nammo recently achieved a world record in a demonstration to the UK’s Defence Science and Technology Laboratory and Royal Navy at the Andoya Test Centre, Norway, where, fired from a shore-based Royal Norwegian Army CV9030N 30mm cannon – simulating a ship-based capability – it destroyed a representative FIAC target travelling at 30kts at a range of 4.8km with the first shot.

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