The railgun, a futuristic electromagnetic weapon that can fire a projectile at seven times the speed of sound, made its public debut at the the U.S. Navy's Science and Technology Expo. (Reuters)

First it mounted a laser aboard a ship in the Persian Gulf. Now the Navy has publicly unveiled another futuristic weapon: the electromagnetic “rail gun.”

In development for years, the weapon would be able to fire a projectile at Mach 7, or seven times the speed of sound, hitting targets 110 miles away. (By comparison, a Hellfire missile travels a little over Mach 1.)

Instead of gunpowder as a propellant, it uses electromagnetic pulses, and the projectiles hit with such overwhelming force that they don’t need to be armed with explosives. The impact from traveling at such amazing speeds is enough, thank you very much. Lasers sizzle rather than go boom, as some have said. The rail gun definitely has one heck of a boom.

The gun made its debut at the Navy’s Future Force Science and Technology Expo at the Washington Convention Center this week.

One top Navy official recently likened the impact to “a freight train going through the wall at a hundred miles an hour.” The lack of gunpowder and explosive warheads eliminates some significant safety hazards for Navy crews, officials say.

By the way, here’s video of that laser:

The Navy is unveiling a laser weapons capability that can be used aboard ships at sea. (U.S. Navy)

[RELATED: With photos and video, Navy shows how its new laser gun works at sea]