It has no gunpowder, no explosive shell and no moving parts except the projectile itself. It also eats its own barrel. The railgun is the weapon navies keep cancelling, and keep coming back to.
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| The Office of Naval Research railgun at Dahlgren fires its world-record 33-megajoule shot, December 2010. Photo: U.S. Navy / John F. Williams, public domain, via Wikimedia Commons. |
In the summer of 2025, a boxy turret on the stern of a Japanese test ship did something no navy had ever done. The ship was JS Asuka, a one-off experimental vessel, and the turret held an electromagnetic railgun: a gun that fires without gunpowder. Over several weeks of trials in June and early July, it shot at a target vessel under tow at sea, and hit it, repeatedly. When Japan's Acquisition, Technology and Logistics Agency (ATLA) released the damage photographs a few months later, the cross-shaped holes in the target's side told the story plainly: a solid metal dart, with no explosive in it at all, had punched straight through at several times the speed of sound.
The strange part is who did it. The United States, which invented the modern naval railgun and spent more than $500 million on it over some 15 years, never got its gun to sea at all. Japan, on a fraction of the budget, did. And in Washington, after formally walking away from the weapon in 2021, the US Navy has quietly started firing its old prototype again, while a newly announced class of American battleships is being drawn with railguns on the plans.
This is a weapon that refuses to stay cancelled. To understand why, you have to understand what it promises, and what it does to itself every time it fires.
A gun with no gunpowder
A normal gun is a controlled explosion. Burning propellant makes hot gas, the gas pushes the shell, and chemistry sets the speed limit: even the best powder guns struggle to push a projectile much past 2 kilometres per second.
A railgun throws the chemistry away. Inside the barrel are two long metal rails, side by side. The projectile sits between them on a fitting called an armature. When the gun fires, an enormous electric current, on the order of millions of amps, surges down one rail, across the armature, and back along the other rail. That current turns the space between the rails into a powerful magnetic field, and the field and the current together produce what physicists call the Lorentz force. The force has only one way to push: it shoves the armature, and the projectile with it, down the rails and out of the muzzle at extraordinary speed.
There is no bang in the conventional sense, because there is no explosion. The crack in test videos is the projectile breaking the sound barrier, plus the violence of that much electricity switching in a few thousandths of a second. The energies are hard to picture, so try the US Navy's own comparison: one megajoule is roughly the energy of a one-ton car travelling at 100 miles per hour. In December 2010, the Navy's test gun at Dahlgren, Virginia fired a record shot of 33 megajoules. Naval prototypes have fired at around Mach 6 to Mach 7, fast enough that a solid slug needs no warhead. At those speeds, the impact itself is the weapon.
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| A railgun test firing at Dahlgren in 2008. The fireball is not an explosion: it is metal shearing off the projectile and igniting in the air. Photo: US Navy, public domain, via Wikimedia Commons. |
Why navies want one so badly
Three promises keep pulling admirals back.
The first is reach and speed. The US Office of Naval Research targeted ranges of 50 to 100 nautical miles at first, with talk of more later, from a gun whose projectiles arrive so fast it could also engage aircraft and missiles.
The second is cost. A modern anti-ship or air defence missile costs somewhere in the region of a million dollars a shot, sometimes several million. The guided projectile developed for the American railgun, the Hypervelocity Projectile (HVP), was estimated in Congressional Research Service reporting at between about $25,000 and $85,000 a round. Even at the top of that range, a ship could afford to shoot at cheap drones, targets no captain would waste a missile on.
The third is the magazine. Missiles are big, so ships carry dozens. Railgun projectiles are compact metal darts, so a ship could carry hundreds, with no explosive propellant to cook off if the ship is hit. On paper, it is the perfect naval gun.
The problems that refuse to die
On paper. In practice, a railgun is a machine that tries to destroy itself, three ways at once.
Power. A single full-power shot needs tens of megajoules delivered in milliseconds, which means capacitor banks and cooling gear that take up serious space. On JS Asuka, the support equipment filled four shipping containers parked on the deck. Only ships with big electrical generation margins can even think about hosting one.
Wear. This is the problem that beat the Americans. The current arcs, the heat is ferocious, and the rails erode with every shot. US reporting put the practical barrel life of the big prototypes at only a few dozen full-power shots before the barrel needed replacing, against a Navy requirement measured in hundreds. A gun that needs a new barrel after one afternoon's shooting is a laboratory instrument, not a weapon.
Rate of fire and guidance. A useful naval gun has to fire repeatedly, six to ten rounds a minute in the US Navy's original requirement, and every shot dumps more heat into the rails. The projectile, meanwhile, has to survive an acceleration that would crush ordinary electronics, then guide itself at hypersonic speed. The HVP showed hardened guidance electronics could survive the launch, which is why it outlived the gun itself: it is now being adapted for ordinary 5-inch naval guns and army howitzers.
America built it first, then walked away
The US Navy's Electromagnetic Railgun programme began in 2005, run by the Office of Naval Research. BAE Systems and General Atomics each built 32-megajoule prototype launchers, tested at Dahlgren from 2012 onward. The guns worked: they set energy records, fired multi-shot salvos, and hit targets more than 100 miles away in land testing. What they never did was go to sea. The planned shipboard test was delayed again and again, and never happened.
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| The full-size prototype launcher at Dahlgren in 2017, the gun that set the records and never went to sea. Photo: U.S. Navy / John F. Williams, public domain, via Wikimedia Commons. |
In 2021 the Navy called time, pointing to budget pressure, the difficulty of integrating the gun with existing combat systems, and newer priorities. Funding was redirected toward hypersonic missiles and lasers, and the prototype went into storage at White Sands Missile Range in New Mexico. The physics worked; the engineering economics did not.
But the story has a second act. In February 2025, the stored prototype fired again at White Sands in a three-day campaign, officially to gather high-velocity data for the Navy's hypersonics office. In October 2025, General Atomics began openly pitching railguns again, this time as a last-ditch air and missile defence layer, including for the defence of Guam, arguing that a decade of work on electromagnetic aircraft catapults and better materials has eased the old wear problem. And in December 2025, the announced Trump-class guided missile battleships were presented with railguns among their intended armament. None of this is a deployed weapon: the ships are years away, and analysts openly question the timelines. But the gun America buried in 2021 is being dug up, carefully, in public.
Japan and China kept going
Japan took the opposite path: smaller gun, steadier pace. ATLA has worked on railguns since the mid-2010s, and deliberately chose a modest 40 mm weapon of about 5 megajoules a shot, with a 20-megajoule gun as the next goal. It made the world's first shipboard railgun firing in October 2023, then in 2025 put a turreted version on JS Asuka and hit a moving target vessel, the first time any navy had done that. Just as important, ATLA says it changed the rail materials away from copper to fight erosion, and reported around 120 stable shots in durability testing. Four containers of support gear on the deck say the power problem is not solved. The turret, the hits and the barrel life say the wear problem is being beaten down. Japan's stated aim is defensive: a gun fast enough to swat down hypersonic missiles.
China went to sea earliest and says the least that can be checked. In early 2018, photographs showed a large railgun turret on the bow of the landing ship Haiyang Shan, with containerised power gear behind it, years before anyone else put one on a ship. Chinese researchers led by Rear Admiral Ma Weiming have since published claims of Mach 6 shots over 100 to 200 kilometres and 120 consecutive firings without failure. Every one of those figures comes from Chinese state or university sources, none has been independently verified, and there is still no confirmed operational railgun on a front-line Chinese warship. What is not in doubt is the pattern: the test ship kept its gun and kept sailing, with further sea trials reported as recently as late 2023. Smaller research efforts exist elsewhere, including the French-German Saint-Louis institute and India's DRDO, but Japan, China and the United States remain the serious players.
At a glance
- How it works: a pulse of millions of amps runs down two rails and across the projectile; the resulting Lorentz force accelerates it out of the muzzle. No gunpowder, no explosive shell.
- Typical test speeds: about Mach 6 to Mach 7 (roughly 2,000 to 2,500 metres per second) for naval prototypes fired so far.
- Range: 100 nautical miles (185 km) or more was the US design goal; long-range hits at 100-plus miles were demonstrated in US land testing.
- Cost per shot: HVP guided projectile estimated at roughly $25,000 to $85,000 in US congressional reporting, against a million dollars or more for a missile.
- Status, United States: programme ended in 2021 after more than $500 million spent; prototype fired again in 2025 for hypersonics research; industry pitching railguns for missile defence; a future battleship class announced with railguns planned. Not deployed.
- Status, Japan: active and leading at sea: shipboard firing 2023, target vessel hit from JS Asuka in 2025. Still a test programme, not a fleet weapon.
- Status, China: test ship at sea since 2018; strong performance claims, none independently verified. Not confirmed as deployed.
- The core problem: rail wear and pulsed power: barrel life in the dozens of shots (US experience) versus the hundreds a fleet weapon needs.
Why they keep coming back
Every navy that has cancelled a railgun has cancelled the same gun: the long-range bombardment weapon promised in 2005. The idea keeps returning because the job description keeps changing. In 2025 the pitch is no longer about shelling targets 100 miles inland. It is about the maths of modern air defence, where a ship with 90 missile cells faces waves of drones and missiles that cost less than the interceptors fired at them. A gun that shoots guided darts at Mach 6, hundreds of rounds deep, at a fraction of a missile's price, answers a problem that did not exist when the programme began.
The physics has not changed. A railgun still eats its rails and still drinks power in container-sized gulps. What has changed is the urgency on one side, and, if Japan's results hold up, the materials on the other. The railgun is not a fleet weapon yet, anywhere. But the country now leading the race got there by treating it as an engineering problem to be ground down, shot by shot, rather than a wonder weapon to be unveiled. That is usually how technology like this eventually arrives: late, smaller than promised, and then, suddenly, obvious.
