[Suicide Junkie]

Hitpoints on weapons are scaled to represent how vulnerable they are to fire.
The mounts should cause only a small increase in the hitpoints of the weapons, representing their larger surface area.

The main problem with having larger armor mounts is that they would then become extremely effective for protecting everything else. You would need to force the player to use a large mount bridge & etc. The hitpoints balance for unmounted components, and should only be altered slightly by mounts.