http://www.onr.navy.mil/en/Media-Cen...-Delivery.aspx

Magnetic fields created by high electrical currents accelerate a sliding metal conductor, or armature, between two rails to launch projectiles at 4,500 mph to 5,600 mph.
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Navy planners are targeting a 50- to 100-nautical mile initial capability with expansion up to 220 nautical miles.
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The EM Railgun program, part of ONR’s Naval Air Warfare and Weapons Department, previously relied upon government laboratory-based launchers for testing and advancing railgun technology. The first industry-built launcher, a 32-megajoule prototype demonstrator made by BAE Systems, arrived at Naval Surface Warfare Center (NSWC) Dahlgren Jan. 30. One megajoule of energy is equivalent to a 1-ton car traveling at 100 miles per hour.