As your ship grows and you move on to harder missions the need for stronger ammo will arise. There are several laser batteries to choose from and several rockets as well. You will find that a selection of each is makes life much easier in the Orbit. Keep in mind that not all the ammo choices are available all the time. So check back often to make sure you get your share of the elite ammo. X4 or whites as many pilots call it can only be acquired through reward for quests, or gates and from the Galaxy Gate Materializer.
The chart below will outline at a glance the ammo you will be working with.