Hmm, interesting. Odd how before people kept saying that beams were useless, which I disagreed with, and now, when I find them quite lackluster, and state as such, people now have a bunch of reasons why they don't suck.
They are good if you are larger than your target, or if they lack shields. IF they have shields, you need at least one size class on them, ideally more, otherwise shields can shrug off most beams. If they have no shields, beams, due to perfect accuracy, tear through armor eventually, and no amount of good flying can do anything.
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This is why I am trying to make a mod that gives beams hard flux damage, and already made a global armor regeneration mod.