- Thus under these changes Plasma Carronades would become a more robust and interesting weapon system to invest in, without losing their low-cost / low-tech niche. HPMs would become shield-buster / ion cannon-esque weapons, and with the option to turret would double as Anti-Fighter / Anti-FAC against beam-centric foes. Mesons would a lot more useful to research as a main weapon option, since the big ones would give better performance against ships while the turreted small ones remain a viable Anti-Missile / Anti-FAC, with the ones in the 12~15cm range would double as Anti-Fighter weapons. These would make Mesons into an actually threatening weapon, without reverting them to the overpowered monstrosities that they were. Add back them Armored Missiles and suddenly they become very, very attractive options indeed. 
A different view on Plasma Carronades, I have always seen them as the short range, super high damage weapon of the game. To that end, in my head, they have been a lot like the Plasma Mortars in the The Last Angel stories. In those, the plasma mortar is a short range devastating weapon that hits harder than just about any other energy weapon and then burns. To that end, I would do something like a certain spoiler's weapon.
To that end, I would make it so that when a plasma carronade hits, it does its damage and then each 5 second tick after the hit, it applies "burn" damage to the same armor columns it damaged in the initial hit. The burn damage would be at most 1 armor in each armor column per 5 second tick. The total amount of burn damage that a hit from the plasma carronade could do would be limited to some percentage of the damage the initial hit did. The percentage could start at 50% and you could have a research line to increase this percent, call it Plasma Control. With a research option you could allow more damage to be caused by the burn, even potentially more than the initial hit.
Example: (Numbers are from VB Aurora so not sure if damage number is the same)
25 cm Plasma Carronade: 16 damage
Damage Template: The damage would be across 7 armor columns and be 4 rows deep.
Time 0: Plasma Carronade hits and causes 16 damage
Time 1 (5 seconds after initial hit): 50% of initial damage is 8, 8 units of burn damage remain to be applied. All 7 armor columns would apply a single point of damage, for a total of 7 burn damage. If any columns with no additional armor rows, then the burn damage is applied to internal ship components.
Time 2 (10 seconds after initial hit): 50% of initial damage is 8, 1 unit of burn damage remains to be applied. 1 armor column applies a single point of damage, choose deepest armor column (ie: the middle column in the damage template). If the column(s) have no additional armor rows, then the burn damage is applied to internal ship components. (Stretch goal: apply burn damage to same components as previous increment if they were not destroyed by previous damage)
Time 3 (15 seconds after the initial hit): 50% of initial damage is 8, all damage has been applied so do nothing.
For a max tech Plasma Carronade, you would do 168 initial damage (24 columns wide, 13 columns deep) and burn another 84 damage across 24 columns of armor resulting in another 3+ rows of armor destruction or internal damage.
Now that is a close quarters devastating weapon.
