Weapon design question

[harlikwin]

I'm trying to figure out how to add some "sci-fi" weapons to the game.

Anyone have suggestions how to implement the following?
Laser: Essentially can hit whatever it can see quite easily, but its effects would be blocked by obscurants and performace degraded by weather effect.
My thoughts are to treat it as a HEAT weapon, with a small warhead size and high penetration.

Plasma gun: Essentially this weapon would have high damage/penetration at short ranges and then dissipate at medium/long ranges.
My thoughts are to use the AP weapon type and set a short range, but I don't think at longer ranges the penetration would suffer enough?