An EM railgun is powered by electricity rather than gunpowder. A shell is launched at Mach 7 through the electromagnetic rails into the atmosphere for about one minute, flies out of the atmosphere for four minutes, and then descends to Earth toward its target at Mach 5 in approximately one minute. The projectile is guided using the Global Positioning System.

it is fast, powerful,precise and you dont have to worry about the
unexpected explosion of projectiles.so its even safer.
The ammo cabin being hit no longer cause big explosion which may sink the whole cruiser.