Likely the projectile will be _much_ smaller since it's supposed to cause damage by kinetic energy transfer instead of an explosive charge. Science fiction lovers will readily recognize the concepts of the railgun and the use of kinetic energy weapons in combat. The obstacles to practical railgun technology are portability, superconducting, room-temperature magnets, and power source. In a short-range weapon, significant velocities could mean laser-like ballistics - a flat trajectory out as far as you can see.