A test shot fires from the Office of Naval Research-funded Electromagnetic Railgun prototype launcher located at the Naval Surface Warfare Center Dahlgren Division.
A story from a little over a year ago reported a 33 MegaJoule test. A blog post at Scientific American puts the design range at 20-32 MJ, so it seems the refinements are now in areas other than the energy (e.g. better efficiency, moving from a research device to a better-engineered on that can be deployed). That article also refines the expected range of the gun.
The Navy says that the railgun project, initiated in 2005, will yield a 20- to 32-megajoule weapon that shoots a distance of 50 to 100 nautical miles (roughly 90 to 185 kilometers).
The best part is that the recoil does not act upon the barrel. Is there an EMP that interferes with twitting, er, tweeting?
Hmm. For some sense of scale, I’ll note that an 8″ gun from ca. 1900 (*http://www.navweaps.com/Weapons/WNUS_8-45_mk6.htm) had a muzzle energy of 41 MJ. I remain skeptical that any electrically-driven weapon, be it a rail gun or a “directed energy” weapon, will replace chemically-driven weapons at any point in the near future.