... I had been hearing in PB that there wasn't a lot of difference between the damage output of the different classes, but maybe that's changed now.
It was mentioned that there are Ship Hardness and Weapon Hardness-Penetration stats in the code, which were not there in PB.
If the ship's hardness is greater than the weapon's hardness-penetration, it takes less damage.
Higher class weapons have a higher HPen value, and larger ships have a higher Hardness value.
I suspect the bulkhead upgrades affect this value too.
So a class 4 cannon should hurt Cobras more than a class 2, and hurt Sidewinders about the same as a class 2.
Really big ships should be able to shrug off class 1 and 2 weapons more easily.
Railguns "Punch above their weight", so the Class 2 is effectively hitting harder than the other class 2's as far as Hardness/penetration goes.