The US Navy is testing a weapon that can fire low-cost 10-kg projectiles at seven times the speed of sound.
The supersonic rail gun uses electromagnetic energy in the form of high-power electric pulses generating magnetic field to fire projectiles with very little recoil.
According to Rear Admiral Bryant Fuller, the US Navy’s chief engineer, the projectiles leave the rail gun with muzzle energy of about 32 megajoules of force. One megajoule of muzzle energy would be enough to move a one-ton object at about 100mph (160kmh).
"It's now reality and it's not science fiction. It's actually real. You can look at it. It's firing," said Rear Admiral Matthew Klunder, the chief of Naval Research.
"It will help us in air defence, it will help us in cruise missile defence, it will help us in ballistic missile defence," he said. "We're also talking about a gun that's going to shoot a projectile that's about one one-hundredth of the cost of an existing missile system today."
The US Navy has funded two single-shot rail gun prototypes, one by privately held General Atomics and the other by BAE Systems. Klunder said he had selected BAE for the second phase of the project, which will look at developing a system capable of firing multiple shots in succession.
The Navy research chief said that cost differential - $25,000 (£15,000) for a rail gun projectile versus $500,000 to $1.5m for a missile - will make potential enemies think twice about the economic viability of entering into conflicts with US forces.
"That ... will give our adversaries a huge moment of pause to go: 'Do I even want to go engage a naval ship?'" Klunder told reporters. "You could throw anything at us, frankly, and the fact that we now can shoot a number of these rounds at a very affordable cost, it's my opinion that they don't win."
According to Admiral Klunder, sea trials of the weapon should be conducted in 2016 with the rail gun mounted on the USNS Millinocket high-speed vessel.
Ships can carry dozens of missiles, but they could be loaded with hundreds of railgun projectiles, he said.
"Your magazine never runs out, you just keep shooting, and that's compelling," Klunder said.