USA Electromagnetic Rail Gun Proposal - NavWeaps- railgun projectile shape ,The railgun was fired at 10.64MJ (megajoules) and the projectile attained a muzzle velocity of 8,268 fps (2,520 mps). US Navy Photograph # 080131-N-0000X-001. The Office of Naval Research (ONR) 32 MJ (megajoules) Electromagnetic Railgun (EMRG) laboratory launcher, located at the Naval Surface Warfare Center Dahlgren Division in Dahlgren, Virginia.Navy Railgun Projectile | DemaxDeNavy railgun projectile. A railgun is a device that uses electromagnetic force to launch high velocity projectiles by means of a sliding armature that is accelerated along a pair of. The navys much hyped electromagnetic railgun may end up dead in the water.