A super-powerful gun that shoots rounds more than 100 miles (160 kilometers) away _ at several times the speed of sound _ is being developed for Navy warships.

The weapon is known as an electromagnetic railgun. It consists of parallel rails and uses a magnetic field and electric current, instead of chemicals, to generate energy to fire the rounds, wh.

The Navy said Tuesday an industry-built prototype of the gun is being tested at the Naval Surface Warfare Center Dahlgren Division in northern Virginia. At this stage, they're focused on measuring the gun's barrel life and structural integrity because it is capable of firing rounds at up to 5,600 miles per hour (9,010 kph), or more than seven times the speed of sound. More research and development is needed to over the next five years to ensure the weapon can cool down and handle repetitive fire. The Navy wants to be able to fire 10 rounds a minute.

They're also working to ensure that the roughly 40-pound (18-kilogram) metal projectile the gun will ultimately fire can withstand the heat and G-forces from the launch and will not disintegrate. And they need to make sure any electronics in the projectile, such as a GPS system, are safe.

Navy researchers said the weapon's high-velocity and range would allow ships to provide support for Marines storming a beach. It could also target enemy ships and provide self-defense against cruise and ballistic missiles.

Currently, 5-inch (12.7-centimeter) guns on destroyers have a range of about 15 miles (24 kilometers).

``As you can see, it represents a significant increase in range,'' Roger Ellis, the Office of Naval Research's electromagnetic railgun program manager, said in a conference call with reporters.

Ellis said that because the gun can fire at such high speeds, it wouldn't necessarily have to shoot an explosive to inflict damage, either. He would only say that it would carry a ``lethal mechanism.''

The Navy has been developing the weapon since 2005 at a cost of about $240 million. Similar funding is expected to keep the program going through 2017, when the Navy anticipates the weapon will be ready. It could still take several more years before the gun is put on ships.

The 40-foot (12.19-meter)-long gun being tested more closely mirrors a final product than previous versions. It has been test fired six times since last week.

A second industry-built prototype will be delivered to the Navy for testing in April.

General Atomics, one of two companies providing a prototype, has also invested $20 million.

``We believe this is definitely a game changing capability that'll enable our forward presence and freedom of the seas,'' said Tom Hurn, director of railgun programs for General Atomics. (AP)