The United States Naval Surface Warfare Center Dahlgren Division
demonstrated an 8 mega-joule rail gun firing 3.2 kilogram (slightly
more than 7 pounds) projectiles in October of 2006 as a prototype of a
64 mega-joule weapon to be deployed aboard Navy warships. Such weapons
are expected to be powerful enough to do a little more damage than a BGM-109 Tomahawk missile at a fraction of the projectile cost.[2]

the prototype of the above weapon was demonstrated in a jane's documentery a few(?) years ago.
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sorry!

neglected to credit source for the first paragraph. wiki.