Published on 18/04/2025
By Yoshihiro Inaba
Naval News
JMSDF picture showing the Railgun aboard the test ship JS Asuka.
On April 18, 2025, the Japan Maritime Self-Defense Force (JMSDF) released an image of its state-of-the-art railgun currently undergoing testing aboard the test ship JS Asuka.
Latest status of rail gun development
In the Japanese MoD, railgun development is conducted by the Ground Systems Research Center (GSRC), a division of the Acquisition, Technology & Logistics Agency (ATLA). ATLA began full-scale development of the railgun in 2016. Under the name “Research on Electromagnetic Acceleration Systems,” the research was conducted from FY 2016 through FY 2022. The target in this research was a muzzle velocity of 2000 meters per second and a barrel life of 120 rounds. In other words, the goal was to achieve stable firing up to 120 rounds at a constant muzzle velocity.
In the case of a conventional firearm, damage to the barrel caused by the pressure generated by the explosion of gunpowder would be a problem, but this does not occur in the case of a railgun. On the other hand, damage caused by heat from the high current flowing through the rail and wear from contact between the armature and the rail is a problem. As the surface of the rail is eroded by this, it leads to performance degradation, such as a reduction in muzzle velocity. Therefore, copper was initially used as the material for the barrel rail, but was changed to a different blend of metals and other materials throughout the research. As a result, it was confirmed that no significant damage occurred to the barrel rail even after 120 rounds were fired.
ATLA achieved the first ship-board firing test of a railgun in October 2023. Based on the results of the research to date, the project is now moving on to “Research on Future Railgun,” which will be conducted from FY2022 to FY2026. While previous research has focused on firing projectiles from the railgun, the current research aims to advance this research into a “gun system” equipped with a series of mechanisms for actual operation. It includes:
On April 18, 2025, the Japan Maritime Self-Defense Force (JMSDF) released an image of its state-of-the-art railgun currently undergoing testing aboard the test ship JS Asuka.
Latest status of rail gun development
In the Japanese MoD, railgun development is conducted by the Ground Systems Research Center (GSRC), a division of the Acquisition, Technology & Logistics Agency (ATLA). ATLA began full-scale development of the railgun in 2016. Under the name “Research on Electromagnetic Acceleration Systems,” the research was conducted from FY 2016 through FY 2022. The target in this research was a muzzle velocity of 2000 meters per second and a barrel life of 120 rounds. In other words, the goal was to achieve stable firing up to 120 rounds at a constant muzzle velocity.
In the case of a conventional firearm, damage to the barrel caused by the pressure generated by the explosion of gunpowder would be a problem, but this does not occur in the case of a railgun. On the other hand, damage caused by heat from the high current flowing through the rail and wear from contact between the armature and the rail is a problem. As the surface of the rail is eroded by this, it leads to performance degradation, such as a reduction in muzzle velocity. Therefore, copper was initially used as the material for the barrel rail, but was changed to a different blend of metals and other materials throughout the research. As a result, it was confirmed that no significant damage occurred to the barrel rail even after 120 rounds were fired.
ATLA achieved the first ship-board firing test of a railgun in October 2023. Based on the results of the research to date, the project is now moving on to “Research on Future Railgun,” which will be conducted from FY2022 to FY2026. While previous research has focused on firing projectiles from the railgun, the current research aims to advance this research into a “gun system” equipped with a series of mechanisms for actual operation. It includes:
Continuous firing of projectile
Fire control system
Stability of projectile after launch
For example, while research thus far had focused on single-shot firings, efforts are now underway to establish continuous firing capabilities. This is because, in actual operational scenarios, railguns would need to continuously intercept incoming missiles or deliver multiple rounds against enemy vessels or ground targets.
Flight stability of the projectile is also being pursued. Even with a railgun, unless the projectile remains stable after leaving the muzzle—just like conventional artillery—it cannot accurately hit its target. Moreover, even if a hypersonic muzzle velocity is achieved, the projectile would rapidly decelerate due to air resistance if flight stability is poor. Enhancing projectile stability and reducing air resistance would not only extend the effective range but also improve overall lethality.
Furthermore, realizing a complete gun system involves more than simply preparing the launcher and projectiles. A fire control system is essential to control the launcher, acquire targets based on external sensor data, predict flight paths and impact points, and ensure precise hits on the target. Research is therefore being conducted on a dedicated fire control system tailored to the railgun, which has characteristics—such as muzzle velocity—distinct from conventional artillery.
In addition, one of the greatest challenges for fielding railguns is securing a reliable power source. Given that the projectile is launched by a massive electric current, sufficient power supply and energy storage systems are critical, especially for continuous firing. While large-scale generators and storage units would suffice for securing power alone, they are not feasible on space-constrained platforms such as naval vessels or mobile land vehicles. As a result, current research efforts also focus on miniaturizing power supply systems alongside the launcher itself.
For example, while research thus far had focused on single-shot firings, efforts are now underway to establish continuous firing capabilities. This is because, in actual operational scenarios, railguns would need to continuously intercept incoming missiles or deliver multiple rounds against enemy vessels or ground targets.
Flight stability of the projectile is also being pursued. Even with a railgun, unless the projectile remains stable after leaving the muzzle—just like conventional artillery—it cannot accurately hit its target. Moreover, even if a hypersonic muzzle velocity is achieved, the projectile would rapidly decelerate due to air resistance if flight stability is poor. Enhancing projectile stability and reducing air resistance would not only extend the effective range but also improve overall lethality.
Furthermore, realizing a complete gun system involves more than simply preparing the launcher and projectiles. A fire control system is essential to control the launcher, acquire targets based on external sensor data, predict flight paths and impact points, and ensure precise hits on the target. Research is therefore being conducted on a dedicated fire control system tailored to the railgun, which has characteristics—such as muzzle velocity—distinct from conventional artillery.
In addition, one of the greatest challenges for fielding railguns is securing a reliable power source. Given that the projectile is launched by a massive electric current, sufficient power supply and energy storage systems are critical, especially for continuous firing. While large-scale generators and storage units would suffice for securing power alone, they are not feasible on space-constrained platforms such as naval vessels or mobile land vehicles. As a result, current research efforts also focus on miniaturizing power supply systems alongside the launcher itself.
ATLA’s Railgun Test from Ship at Sea
Engaging Enemy Vessels from Coastal Positions to the Open Sea
Now, if railguns were to actually be deployed by the Self-Defense Forces, what operational uses are envisioned?
According to ATLA documents, railguns are expected to be employed as naval or land-based artillery systems. In the naval role, they would likely be used to intercept incoming anti-ship missiles—especially hypersonic cruise missiles, which are considered difficult to counter due to their high speeds. By leveraging the railgun’s high velocity and extended range, a layered air defense network could be established in conjunction with shipborne surface-to-air missiles.
For land-based systems, counter-battery fire against enemy artillery units located deep behind the front lines—similar to the role of traditional howitzers—is naturally envisioned. Thanks to the railgun’s advantages of reduced time-to-target and greater range, it would be possible to conduct out-ranging strikes against enemy artillery units. Moreover, ATLA documents also illustrate the concept of using railguns as coastal artillery, engaging enemy vessels operating in the open sea. The expectation is that hypersonic projectiles would penetrate enemy warships and destroy critical compartments.
Regarding projectiles, research will not be limited to armor-piercing rounds but will also extend to technologies for airburst munitions—rounds that detonate mid-air to disperse lethal fragments—optimized for anti-air warfare scenarios. Having transitioned into the development of a full-fledged “gun system,” railguns are now poised for broader operational studies and steady technological maturation as a future defense asset.
Japanese, French and German cooperation in railgun technology
Japan’s ATLA and the French-German Research Institute of Saint-Louis (ISL) signed last year a Terms of Reference (TOR) with the objective “to explore the possibilitiy of collaboration for research, development, test and evaluation of Railgun technologies”.
Naval News interviewed at the time representatives from all parties about this cooperation.
Naval News learned recently from an ISL representative that the cooperation is going well and that Railgun engineers have been exchanged: ATLA engineers are at ISL in France and ISL engineers have been sent to Japan.
Yoshihiro Inaba is a Freelance Writer based in Shizuoka, Japan. He is one of the few young military writers in Japan and is currently a student studying international law (especially self-defense and use of force) at a Japanese graduate school. He is particularly familiar with Japan's Ground, Maritime and Air Self-Defense Forces.
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