Besides the colony, grenade launchers aren't doing too hot, especially in PvP. I thought of a few simple fixes.
1. Buff PvE damage by 25%-50%.
2. Increase ammo capacity by 30%-50%.
3. Increase projectile size by 50% to increase chances of hitting a target.
-
Been using the IB one and it's a beast, same damage as wicked sister but far better stat rolls. Give it a go, you just have to be able to aim which is the only problem with the colony. It one hit kills in pvp so I can't see a reason for a damage buff, maybe a slight (25%max) increase of blast radius but even then I find the one I'm using to be fine. However, they will never be meta because it's not easy to use for max damage.