Here is a primer on railgun technology Using Electromagnetic fields projectiles will be almost six kilometers/second. The number of rounds fired per ship would jump from 232 to 5000. The destructive force those rounds deliver would more than double, from 6.6 megajoules to 17. The rounds would fly almost five times farther — up to 300 nautical miles.
More on electromagnetic railguns

General Atomics Aeronautical Systems has won a $9.6-million, 30-month contract for the preliminary design of an electromagnetic launcher. This weapon could be fielded between 2014-2019.