Obviously the name would be different, more interesting, but as I had this idea kind of just randomly occur to me, I figured I'd share it.
The exact details aren't things I've thought through all the way, so I'll probably tweak these in future posts (or waste a mod's time asking them to change the post since we can't edit our own posts unlike on every other forum I've ever been on), but here is a rough concept for a new gun. This can be either Heavy or Light, I'm not too picky which.
Primary Damage: Impact (moderate-to-low damage for weapon type)
Secondary Damage: Piercing (moderate-to-high damage for weapon type)
Ammo: 1
Reload: 4
Range: Very Long
AoE: Not sure, but probably on the large side
Horizontal Arc: 80
Vertical Arc: 20
Special: When fired, the projectile will arc around back toward the gun (based on where the gun fired), flying toward the 0-degree point for the gun (so a projectile shot to the left will arc back toward the right). The projectile has a flight time of 8 seconds before it will finish returning. If it hits something, it does not return. The projectile has friendly fire turned on (if the ship is still at the place where the shot was fired, and it hasn't hit something else, it will hit the ship (and the gun) that fired it.
The turn speed for the projectile would be such that if fired all the way to the left, it would go out to maybe 20% of the maximum straight distance it can travel, and end up coming back at the ship from the right of where it was fired (also at an 80 degree angle). Reducing the range of the shot will also reduce the Flight Time.