Professional Notes: Prepare Gun Crews for Combat

By Gunner's Mate First Class Wayne Moore, U.S. Navy

Many features make the MK 46 an improvement over the MK 38, including: armor-penetrating capacity using the armor-piercing fin-stabilized discarding sabot (APFSDS) round, more lethal ammunition including the high-explosive incendiary tracer (HEI-T) round, and increased effective range. Crews can operate this weapon system from inside a controlled environment using its remote operating capability. Once the MK 46 is sighted-in, and current ballistic and environmental factors accounted for, any gunner can sit at the console and fire accurately on target.

There are key ways to maximize the effectiveness of this GWS. To sight in the system and complete the ballistic setup, a gun crew must compute the “system zero” and “ammo zero” settings by firing each type of round to configure the inputs. This is similar to sighting in a rifle by adjusting windage and elevation to ensure accurate point of aim and point of impact.

Because the MK 46 is a dual-feed weapon system, it is possible to have multiple round-type combinations. HEI-T rounds can be in the left feed, and armor piercing rounds in the right, for example. Unless the same type of ammunition is in each feed, however, a crew cannot enter a system zero setting in the ballistic settings via the remote gun console. Firing both types of ammunition would enable the gunner to calculate the ballistic settings for each ammunition, adjusting system or ammo zero. The weapon could be re-fired until the rounds impact on target and inputs can be noted and calculated for future firing. To enhance the gun’s accuracy, barometric pressure, windage, pitch-and-roll data, air temperature, ammunition temperature, and lead mode can all be dialed in.

The MK 46 training practice tracer (TP-T) round is effective for training as it allows crews to practice fundamentals—such as trigger control—and qualify, and it tests the functionality of the gun. During workups and certification, a ship’s gun crew will only put TP-T rounds through the barrel and provide ballistic inputs for that type of ammunition only. The training round, however, does not allow crews to fully and optimally prepare themselves and the weapon system for combat.

Using ballistic inputs for TP-T ammunition is ineffective and inaccurate for full caliber ammunition types (as needed to maximize the cannon’s effective range). Gun inputs for TP-T rounds are made with the point of impact for that round type, which has a much shorter maximum effective range than the weapon system’s designed range of 4400 yards. Training with TP-T rounds only, therefore, hamstrings a gun crew by exposing them to just a fraction of the weapon’s capability. Shooting the gun at its maximum effective range in a training scenario can only be done under proper conditions and with expensive non-training rounds, but the additional trigger time and experience with live ammunition would enhance combat proficiency.

Unfortunately, even if ships are allowed to train with HEI-T rounds, the applicable maintenance requirement cards for the MK 46 require the user to zero out the azimuth and elevation inputs, losing the ballistic settings for round type, and forcing the gun console operator to readjust the system zero during an actual firing. Because full caliber ammunition is never shot during training, gun crews have no useful ballistic inputs at the ready. Ships must rely on the skill and proficiency of gun operators to make on-the-fly adjustments to the weapon system. In a controlled training environment, it is possible to shoot, adjust, re-shoot, and adjust as needed to obtain the necessary ballistic inputs. In a combat situation, however, with an enemy fast approaching, the immediate need to protect the ship would not provide the luxury of time to adjust the gun. Once the MK 46 is sighted in through firing and practice, the system inputs would remain constant for the man-machine interface until time to re-boresight the weapon, new crews need to qualify, a system casualty, or new ammunition types are provided.

The manufacturer of the TP-T round states that it is ballistically matched to that of the HEI-T round. To fire with the greatest accuracy, however, each round type should be fired and sighted-in independently prior to being used in a combat situation. Firing only TP-T rounds is cost-effective, but “training like you fight” and being prepared for a combat situation requires shooting “full-up” rounds during work-ups.

The MK 46 is a potent, accurate self-defense gun. To maximize its full capabilities, Navy gun crews need to train with not just TP-T rounds but the full range of ammunition in their ships’ magazines. Firing HE/AP rounds during work-ups will expose gunners to the weapon’s full capability and allow them to boresight the gun for those rounds. Training like we fight requires the use of expensive live ammunition, but it will make our gun crews more lethal when the time comes to fire at an enemy.

*Note: On the LCS-class ships, this gun is called the MK 50.

Petty Officer Moore serves on board the USS Somerset (LPD-25). His next assignment will be as a small-arms instructor at Recruit Training Command Great Lakes.


Conferences and Events

View All

From the Press

22 February - Book Discussion

Thu, 2018-02-22

28 February - Book Talk

Wed, 2018-02-28

Cathryn J. Prince

Why Become a Member of the U.S. Naval Institute?

As an independent forum for over 140 years, the Naval Institute has been nurturing creative thinkers who responsibly raise their voices on matters relating to national defense.

Become a Member Renew Membership