“Navy Mk38 Gun Systems Gaining Co-Axial Small-Caliber Machine Gun” –Seapower

7.62 mm Chain Gun as Coax as optionally installed on 25 mm Mark 38 Mod 3. Image copyrighted by NAVSEA Dahlgren.

The Navy League’s online magazine Seapower is reporting that ” The Navy is installing a co-axial 7.62 mm machine gun on the mounts of its Mk38 chain gun systems, a Northrop Grumman official said….the addition of the co-axial Mk52 machine gun gives the gunner another “right-sized” option for countering a small target, such as pirates or terrorists on jet skis…Northrop Grumman is installing the Mk52 guns in the Mk38 under an indefinite delivery/indefinite quantity contract.”

This has been proposed for several years now, but this is the first indication it is happening. The proposed weapon, the 7.62mm Mk52, is in fact an electrically powered chain gun like the 25mm Mk242. (The article appears to be incorrect in this regard.)

The article also discusses the possibility of upgrading the Mk38 by replacing the 25mm gun with guns of 30 or 40mm.

I think the Coast Guard could make a good argument for upgrading its Mk38s to 40mm. The change would make very little difference to a DDG, also equipped with a 5″ gun and anti-ship missiles, but the Mk38 is the largest weapon available on about 75 Coast Guard cutters and these cutters could at any moment be required to face a vessel much larger than the Iranian boats the Navy has been fixated on. We already know the 30mm is a quantum leap in capability compared to the 25mm. Effectiveness is closely related to projectile weight. The 30mm projectile weighs about twice that of the 25mm. The 40mm projectile will weight three to four times as much as the 25mm. Since the rate of fire for these guns is similar, the 40mm is likely to be at least three times as effective against more difficult targets and also has a greater effective range.


The Coast Guard plans to install the Mk 38 on 64 Webber class and 25 Offshore Patrol cutters. The older crew served version of the Mk38 is on the remaining 378s, the 210s, and the remaining 110 foot Island class WPBs. I expect we may see the Mk38 on the Polar Security Cutters and the 87 foot Marine Protector class WPB replacement when they are built.

This would of course be less important if the vessels had something like the Long Bow Hellfire, which would be more effective than any of these guns against virtually any size targets.


15 thoughts on ““Navy Mk38 Gun Systems Gaining Co-Axial Small-Caliber Machine Gun” –Seapower

  1. Gee, a sub-caliber attachment. Who would have thought of that. Well, the Coast Guard did in 1935 when it “piggybacked” a 30-006 Lewis machine gut on a 1-pounder. Amazing how things go in circles.

  2. I see little value of adding a 7.62 mm c0-axial gun to the Mk 38 mount. The CG should move ahead of the Navy and upgun its cutters with at least 35mm RWS. Better yet would be hand missiles like the Spike-ER on the current mounts. Otherwise the CG will get stuck with gun mounts the Navy wants down the pike sometime?

    Both 30mm and 35mm ordance is available in the DOD inventory. Its the mounts which are not specific to the Coast Guards’ needs.

  3. Has the Coast Guard looked into upgrading the mounts with piggyback missiles such as the STINGER or HELLFIRE? The US Army has developed a similar mount for short range air defense (see link). IMHO this appears a way to increase both the fire power and self defense capabilities without greatly increase the weapons foot print on the vessel.


    • When Stingers were deployed on Navy vessels they had to build cages for the operator to prevent damage to vessel and injury to other people from the back blast. The USCG had the same problem with the LAW in Vietnam. Many a bridge window was blown out from careless firing.

      Why not look a bit more forward. The Coast Guard, and USRCS before it, looked to easy and cheap when it came to ordnance. Only when a national need arose did it upgrade. Look at the Secretary Class (327-foot) cutters. They initially installed the manual 5″/25 mounts even though the 5″/38 was available. An upgrade light weight 5″/54 was available for the FRAM Hamilton class but the Coast Guard went cheap with the 76mm.

      The Coast Guard cares little about ordnance. The cyclic nature of its armaments is the real stuff of history.

      • The mod 3 is the Israeli Typhoon mount.
        They are Capable of having two Spike NLOS missiles with more range than a vertical launch Hellfire. The Philippines and others are doing this.
        If these were mounted there would be less reason to increase the caliber of the gun itself as they would do more damage than bust of 30mm and at much greater range. So the CG wouldn’t have to pay the expense of not only upgunning the cannon but avoid the expense of ammunition and support for a 30mm as well.
        These are canisters not “naked” missiles on a rail and don’t present as military an appearance…which is good way to give the CG some small missiles without bad PR.

      • Bill, I think you mean 5″/51 vice 5″/25. The 5″/51 was an older gun but it was still viable as an anti-surface weapon, while the 5″/25 was primarily an anti-aircraft gun and the 5″/38 a dual purpose weapon.

        The weapons we did get (5″/51s and 3″/50s) had all been developed by the end of WWI, so it may have just been the Navy giving the Coast Guard its cast offs. The 327s Navy half sister ships, Charleston and Erie, were given new 6″/47 guns which were much better anti-surface weapons and the then new 1.1″ anti-aircraft guns.

        Luckily the 327s that fought in the North Atlantic had little need for anti-aircraft weapons, although they might have helped Taney during Pearl Harbor attack.

        The choice of 76mm over 5″/54 for the FRAMed 378s may have had something to do with weight, but easier maintenance might have been an issue.

      • Yep, my misremembering on the guns. Following WWI the Coast Guard “upgraded” to both 3 and 4-inch guns. The 4″/50 and 3″/50 aboard the destroyers. Only two cutters had the 5″/51 in 1925. The rest carried 3″/50. Some cutters continued to carry the 6-pounder. Of course, the 4″/50 left with the destroyer’s return to the Navy. Otherwise, the same types of guns remained in service into 1940-1941.

        I knew the guy who pushed the 76mm. A former FT who liked toys. The Light weight 5″/54 could have been set virtually on the same foundation as the 5″/38. The Coast Guard could have saved huge amounts by not having to extend the 01 deck forward. I never worked on the 76mm but from what I’ve been told it was no joy for maintenance.

      • Yes the 5″/54 Mk45 was designed as a drop in replacement for the 5″/38 that we had on the 378s. and we could have used the Mk92 fire control for it as well.

    • Textron is showing a small Hellfire VLS designed for use with their CUSV.

      It looks to be single or dual cell. In either case, it is quite a bit smaller than the Hellfire VLS being installed on LCS.

      My point is, if this launcher can be accommodated by the CUSV which is roughly 40 feet in length and 8 tons in weight, it should be small and light enough for use on the Fast Response Cutter and other CG assets.

      As other have mentioned, a small load out of Longbows housed in a discrete “VLS box”, along with
      the Mk38 has some merit.

  4. I have been following this conversation for a long time, have done 4 ships, we shot our weapons zero times against aggressors. killed the fuck out of some 55 gallon drums. short of war, why do we want to turn our ships into battleships. I get having the ships have space and power reserves for war time, but jeso peetso you guys are ready to make an frc into the uss Missouri. I think the nscs and opcs should be ready to go escorts but holy crap guys, next thing you will want 16″ 50s on 87s.

      • Chuck put forth a couple of scenarios where an upgunned cutter would make sense.

        I’m certainly not advocating long range anti ship missiles or attempts to turn the FRCs into FACs. I do think though there is a middle ground here where fairly conservative upgrades in armament could enhance the capabillities of FRCs and other classes without negatively effecting the primary missions of the ships.


  5. @Malph, I had seen a model of an unmanned surface vessel (CUSV) with Hellfire in small VLS systems at the stern, but so far I had not seen any indication they were actually being built. Have you seen anything more? Adding Hellfire would certainly decrease the need for an upgrade to the gun.

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