This needs to be near the top of their list. It's bad enough only 2 weapons per faction can even equip these things, and the carbines than can are basically downgrades because they have lower RoF than the stock guns they are variants of, but for then not to work like a 3rd of the time is just ******.
For me, it's consistently the 2nd round of the grenade launcher that does no damage. It's gotten to the point that I don't even bother with the 2nd round (or getting additional ammo).