Locations
Contacts

Endre Lunde

Senior Vice President, Communications

MAIL P.O. Box 142, NO-2831 Raufoss, Norway
VISIT Enggata 37, 2830 Raufoss, Norway
EMAIL endre.lunde@nammo.com
TEL +4790853270

Norway

Nammo AS

MAIL P.O. Box 142, NO-2831 Raufoss, Norway
VISIT Enggata 37, NO-2830 Raufoss, Norway
EMAIL info@nammo.com
TEL +47 61 15 36 00

Quick facts about Nammo’s 30mm “Swimmer”

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 short time of flight, high impact energy and maximum penetration capability out to more than 4 000 m.

  • Projectile Weight: 230g
  • Muzzle velocity: 1430 m/s
  • Max. dispersion: <0.4 mils at 1000m
  • Penetration: >100mm RHA at 1000m
  • Service temperature: -46°C to +63°C
Contacts

Jan Hasslid

Product manager, Nammo

EMAIL jan.hasslid@nammo.com
TEL +47 464 20 388

Audun Dotseth

Director International Sales & Marketing, Nammo

EMAIL audun.dotseth@nammo.com
TEL +47 414 57 077

Endre Lunde

Senior Vice President, Communications

MAIL P.O. Box 142, NO-2831 Raufoss, Norway
VISIT Enggata 37, 2830 Raufoss, Norway
EMAIL endre.lunde@nammo.com
TEL +4790853270

Norway

International Sales and Marketing

MAIL P.O. Box 142, NO-2831 Raufoss, Norway
VISIT Enggata 37, NO-2830 Raufoss, Norway
EMAIL globalsales@nammo.com
TEL +47 61 15 36 00

The Bullet That Swims

Few things are more effective at stopping a bullet than water. Except this one - the Swimmer goes straight through.

Quick facts about Nammo’s 30mm “Swimmer”

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 short time of flight, high impact energy and maximum penetration capability out to more than 4 000 m.

  • Projectile Weight: 230g
  • Muzzle velocity: 1430 m/s
  • Max. dispersion: <0.4 mils at 1000m
  • Penetration: >100mm RHA at 1000m
  • Service temperature: -46°C to +63°C
Contacts

Jan Hasslid

Product manager, Nammo

EMAIL jan.hasslid@nammo.com
TEL +47 464 20 388

Audun Dotseth

Director International Sales & Marketing, Nammo

EMAIL audun.dotseth@nammo.com
TEL +47 414 57 077

Endre Lunde

Senior Vice President, Communications

MAIL P.O. Box 142, NO-2831 Raufoss, Norway
VISIT Enggata 37, 2830 Raufoss, Norway
EMAIL endre.lunde@nammo.com
TEL +4790853270

Norway

International Sales and Marketing

MAIL P.O. Box 142, NO-2831 Raufoss, Norway
VISIT Enggata 37, NO-2830 Raufoss, Norway
EMAIL globalsales@nammo.com
TEL +47 61 15 36 00
Thorstein Korsvold, 20 May, 2020

Nammo’s Swimmer bullet is the result of a unique cooperation between Nammo and the US Navy. A concept that combines armor piercing with the ability to shoot straight through water is being rolled out in significant numbers, for the first time.

Jan Hasslid, one of Nammo’s lead engineers on the project, explains how the Swimmer started out as an armor piercing ammunition.

– The original Mk258, (the predecessor to the “Swimmer”), was designed for use with the Norwegian army’s combat vehicle, the CV90. Test results were really good when the ammo was fired from their 30mm Bushmaster cannons – we could defeat armored vehicles at a distance of 4000 m, Hasslid says.

But when the US Navy started looking at the ammunition, they saw even more potential.

Jan Hasslid

US Navy engineers had an idea about shooting straight under water, and with the robustness and performance of the new Mk258 ammunition we found out that the impossible was actually possible.

– We worked with US Navy engineers to qualify the Mk258 for use with USMC amphibious vehicles. US Navy engineers had an idea about shooting straight under water, and with the robustness and performance of the new Mk258 ammunition we found out that the impossible was actually possible, Hasslid explains.

Under the right circumstances, a bullet can create a bubble as it goes through water. This leads to an effect known as super cavitation, where low pressure behind the bullet reduces drag drastically.

30mm “Swimmer” demonstration video:

But getting there is a daunting technological challenge. It means creating massive pressure at the tip, enough to lower pressure behind it (using the venturi effect), which in turn transforms the water there into vapor.

– We already had something that we knew worked well against armored targets. In addition, our engineers utilized the latest of materials technology, hydrocode simulation tools, as well as Computerized Fluid Dynamics, CFD, to maximize performance of the new design. It took a lot of effort, but we got it to work, Hasslid says.

In addition to just being effective against its intended targets, the main advantage of the Swimmer is versatility. Having just one ammunition type that works against multiple target types – instead of several that need to be changed – makes units more effective in battle. It also helps the logistics chain.

Jan Hasslid

I’m also very optimistic about what we can counter with this: torpedoes, mines or even submarines could all be within range.

Both the US Army and the US Navy are now using the Swimmer. In addition to the new capabilities, that also means less switching between ammunition types. The implication is pretty straightforward: Submarines, torpedoes or other underwater systems become more vulnerable. Instead of using expensive and specialized counters, defenders can now simply fire at such threats, with the guns they have.

– The interest in the Mk258 is tremendous, and it is now being fielded with the most modern weapon systems for US Army and US Navy. I’m also very optimistic about what we can counter with this: torpedoes, mines or even submarines could all be within range, Hasslid concludes.

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About the author

Thorstein Korsvold

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