The US Navy is quietly pushing ahead with a radical new cannon that one day could transform how wars are fought, even though some Pentagon officials have voiced concerns over its cost and viability. Named the railgun, the weapon in question represents a paradigm shift in ballistic technology. Instead of using gunpowder and explosive charges to shoot a shell from its barrel, it employs vast amounts of electromagnetic energy to zoom a projectile along a set of copper-alloy rails. Thanks to four small fins on its rear, the hefty round can then be guided toward a moving object – such as an enemy ship, drone or incoming ballistic missile – relying purely on the kinetic energy from its vast momentum to destroy the target. Ultimately, scientists expect the railgun rounds to travel at speeds up to Mach 7.5, which at 9,100km per hour is more than seven times the speed of sound, and cover a distance of about 160km. "The railgun is revolutionary in terms of how much it can accelerate the bullet,"