I use 1 piece of armour for any designs below 500 size. Or not at all if I really need that 1 space.ORIGINAL: feelotraveller
So you build all of your ships without armour? [X(]
Then maybe 2 pieces of armour; if I have 1 space left, because I rather have a vector engine if I have 2 space leftover.
This is before robotic repairs and the last two armour pieces. Never more than 20 armour even for size 1500 ships.
It isn't that rail guns are overpowered, it's just that armour are near useless. Armour is meant to counter railguns but they don't. By the time their reactive rating is high enough to prevent railgun damage, any railgun tech spent, is better spent on some other weapon instead, because of robotic repairs and bad railgun scaling techtree. Robotic repairs combined with reversed railgun/armour scaling is just the overkill that makes railguns useless in the end/mid game.
There are 5 weapons in the game and armour is only effective against one of them which becomes bad when robotic repairs is researched. Unless somehow, you are preparing for war solely against railguns, you never really want to use more than a few armour.
As for Impact Assault Blasters compared with Shatterforce Lasers, neither matter against armour, because at that tech level, both beans seem to ignore armour anyhow. It is just better to use 10 space for shields so you don't get damaged components instead.