The US Navy, via the Naval Surface Warfare Center Dahlgren Division (NSWCDD), has unveiled the latest iteration of its MK 38 close-in defence autocannon system.
The Mod 4 is the latest version of the MK 38 family. It fully integrates the gun with the Lockheed Martin Aegis combat system and strengthens defence against unmanned aerial systems and high-speed, manoeuvrable unmanned surface vehicles.
The Mod 4 also delivers the weapon’s first calibre increase in more than 30 years, from 25mm to 30mm.
“It is going to greatly improve the ship’s ability to counter modern threats,” said Danny Mudd, technical program lead for MK 38 Mod 4. “With the added caliber, we can reach farther and deliver more damage.”
Introduced in the late 1970s, the original MK 38 system was built around the 25mm MK 242 Bushmaster chain gun, a fully power-operated weapon mounted on the MK 88 support structure. Numerous upgrades in the years that followed saw improvements such as remote control operation and mount stabilisation; the introduction of modern electro-optical (EO)/infrared sensors and a laser rangefinder; improved ammunition handling; and integration of a 7.62mm coaxial chain gun.
The newest upgrade features several improvements, including the Northrop Grumman MK 44 Bushmaster II 30mm gun – now capable of employing air-burst munitions – integrated with the MK 48 Mod 2 EO sight system and the MK 134 Mod 0 operator console. This setup transforms the MK 38 Mod 4 into more powerful and more precise weapon system capable of handling modern threats.
An optional 12.7mm coaxial heavy machine gun further expands engagement options and improves responsiveness against a range of threats. The new sensor is fully stabilised and off mount, enabling better accuracy tracking and clearer imagery in challenging visibility.
A July 2022 test on NSWCDD’s Potomac River Test Range successfully identified, tracked and engaged both surface and aerial targets using live ammunition against fixed and moving targets. It also highlighted the enhanced fire-control chain, the 30mm gun’s improved performance, and its ability to counter new challenges.
USS Mustin, an Arleigh Burke-class Aegis guided-missile destroyer, was the first US Navy warship to receive the upgrade. NSWCDD is now finalising the configuration so the system can be introduced to a wider set of platforms as fleet requirements evolve.