Mk38 Mod4 Gun Weapon System. MSI-Defense Systems

TWZ (The War Zone) brings us a report on the Mk38 Mod4. 

Apparently the USN still has made only one installation. As to the future,

“The Navy’s 2027 fiscal year budget request, released earlier this year, makes clear the plan is still to integrate the Mk 38 Mod 4 at least on all Flight IIA and Flight III subvariants of the Arleigh Burke destroyer. The Mk 38 Mod 4 is also set to be a feature on future U.S. Coast Guard icebreakers, which will also have combat systems derived from Aegis.”

Unfortunately not much new here and perhaps the news is that there is no news about this  being used on future cutters. I checked the MSI–Defense Systems US LCC web site and there has not been a news release about the system since April 2024.

It may be that, with the Navy replacing close to one hundred Mk38 Mod 2/3 with Mod4s on Burke class destroyers, the Navy will pass these replaced units on to the Offshore Patrol Cutters, Arctic Security Cutters, and the remaining FRCs rather than buy new Mod4 mounts. Even if that is the case, there is still the option of upgrading the gun to 30mm.

I asked AI, if the Coast Guard was getting the Mod4 system, and this is what I got.

Yes, the U.S. Coast Guard intends to acquire and field the Mk 38 Mod 4 Gun Weapon System (GWS), but strictly for specific new ship classes like the upcoming Polar Security Cutter (PSC) heavy icebreakers.

Key Details on the Adoption

• Platform Application: The 30mm Mk 38 Mod 4—which upgrades the traditional 25mm chain gun to a 30mm Northrop Grumman MK44 Bushmaster II with a coaxial .50-caliber machine gun and independent electro-optical sight—is slated for the Coast Guard’s heavy polar icebreakers.

• Wider Fleet Rollout: Aside from the Polar Security Cutters, the Coast Guard has indicated the system will go on “some new cutters,” but hasn’t designated a broader fleet-wide replacement.

• Existing Cutters: The Coast Guard has stated it has no plans to retrofit or replace current 25mm systems (such as the Mk 38 Mod 2/3 variants found on Fast Response Cutters) with the new Mod 4.

The Coast Guard really needs to upgrade its existing 25mm mounts to 30mm. As noted in the text,

“The Mk 38 Mod 4 Machine Gun System (MGS) is an upgrade … to address deficiencies in meeting Counter Unmanned Aerial Systems (C-UAS) requirements,” the Navy has said in the past. “In addition, the upgrade will also improve performance against surface targets and maintain Anti-Terrorist / Force Protection capabilities.”

Looking at replacing the Mk38 Mod3’s 25mm gun with the 30mm Mk44 Bushmaster II might give us most of the advantages of the Mk38 Mod4 without the need replace the mount.