More Splodey

I don’t feel like writing today.

The US Navy in the early 1990s was greatly concerned with small boat swarming attacks on US surface ships, and looked at ways to counter them. A couple of different weapons were used. First, ships in areas likely to face such swarm attacks (that is, in the Persian Gulf) were quickly equipped with .50cal machine gun mounts. But the .50cal is not terribly accurate, nor particularly lethal.

A more advanced approach was to modify the 20mm Phalanx Close In Weapon System giving it the capability to engage not just missiles, but also surface targets. 

A third option was to bolt on mounts of automatic cannons. In the end, that’s what happened, with the 25mm M242 Bushmaster cannon on the Mk38 mount.

Photo: Gunner's Mate Seaman Daniel A. Wright fires an Mk-38 machine gun

Mk38 Mod 1 Mount for M242 25mm gun.

For years, the mounts were swapped in and out as ships entered and departed the 5th Fleet Area of Operations. Originally little more than a pedestal mount, todays Mk38Mod2 mount is a remotely operated, stabilized mount with day and night capability.

Mk38 Mod 2 Mount

Part of the decision making process (but only part) of what gun to mount included studies of the terminal effects of the various cannon rounds and ammunitions available. And that’s were this video comes in.



Damn shame to see the MkIII PB getting shot up. It would have been nice to see that up for surplus sale.

4 thoughts on “More Splodey”

  1. The video ends by noting that the 30mm was far more effective than the 25mm so why did the Navy choose the 25mm?

    1. Firstly, cost. The M242 and the ammunition were already in service in large numbers. Literally thousands in service with the Army and Marines. Skimming a couple dozen guns for the Navy posed no real challenge. Secondly, the M242 is relatively light. Just a couple hundred pounds. It’s associated mount could similarly be very light, at least for the manually operated Mk38Mod1. Basically, the mount was/is simply bolted onto a flat surface, and a power cable run to it.

      The lager 30mm gun would need a significantly larger mount. So far, the only qualified mount for it in naval service is the Mk46, which is a far more involved installation. I suppose they could have built a smaller pedestal mount similar to the Mk38Mod1, but even then the large weight and recoil might have called for reinforcement and greater care in selecting where to place the mount.

  2. “But the .50cal is not terribly accurate, nor particularly lethal.”

    I’d like to make a qualifying statement there about the type of targets you’re engaging, small boats being hard to sink with non-explosive rounds, and how firing from a pitching deck by hand without stabilization can affect accuracy. A .50cal is pretty damn accurate and lethal when engaging reasonable targets for a heavy machine gun.

    1. Correct- the gun itself is quite accurate. But the mount used by the Navy, coupled with both the motion of the target and the firing platform, isn’t.

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