So, to throw in my half a cent (because I'm cheap like that), here's an idea that includes experimental math!
I remember a time in dev app where there were two special ammo types that basically were Charged ammo, but favoring either primary or secondary damage (depending on which one was loaded). Now, while this was niche ammo, it was too similar to Charged IMO, and basically had no purpose. Charged was better in every case, especially as both types damaged the gun.
So, here's a much improved version of the original concept, that takes it in a totally different direction.
Instead of increasing the damage of the gun, this ammo modifies the modifiers. There are two options available to go with here, so I'm gonna cover them both.
Option 1: The damage modifiers for primary and secondary damage are all increased by 0.2 (to throw out a theoretical number for the sake of example). Not sure what the negative effects could be, but they'd probably be similar to Charged. No direct effect on the damage the gun actually deals though.
The Effect:
The damage is clearly more all-around than what you get with Charged. This makes it good for guns that aren't really all that accurate, as it can give them the ability to deal damage to more than just the 1 thing they're good at in situations where they can't keep focused on that one thing. A Gatling on a squid comes to mind. While it might be capable of taking down the hull armor completely if you hit with most of the shots, on a ship that moves so fast, it's relatively easy to miss the hull and hit everything else instead. With this ammo, while it's still bad to be missing the armor, at least you're still doing something effective. And while Charged could make you more effective in general as well, this makes your gun better at the things it's bad at as well as the thing it's good at, increasing the number of viable targets the gun can hit without sacrificing viability. Though obviously charged is still better in situations where the gun is more likely to be successfully used in it's primary role only (like a Metamydion).
Option 2: The ammo affects only primary or secondary damage (effectively it's split into two like the original concept that inspired this), perhaps with the modifier for the improved damage increasing by 0.3 instead of 0.2. Probably reduces the modifier for the other damage by a small amount, like 0.1.
The Effect:
With this version, I think the modifier would have to be a bit higher than the other because of the lack of increased damage on the second type, but this could result in OP weapon setups, thus the suggestion that the non-primary type take a penalty (if a small one). As you see in this example, now Artemis does NO damage to the Hull with it's secondary damage, and very little against balloons and armor, though it's primary damage is significant overall (if still lower than Charged in the Hull damage).
Either option really provides a powerful tool really. I'll let you guys discuss it from this point on though.
Another idea along a similar thought process is an ammo that doubles the armor/health of the gun, but reduces the modifiers by a significant amount (0.3, maybe even 0.5).
