I have the Sheltering Module (Immune to explosive damage) and the Cluster Launcher as a main weapon and the Corrosive Drone (which fires when I fire my main gun).
The Cluster Launcher explicitly doesn't count as explosive damages, and my Sheltering Module doesn't prevent me from damaging myself with my Cluster Launcher. My secondary (energy) weapon is powerful but using only it would make my Corrosive Drone useless.
I'm very disappointed with this anti-combo. I'm proposing here a pair of tweaks; I think they are interesting both independently and together (implementing only one of them would be okay, IMO). Tell me what you think of it.
1) The Cluster Launcher could deal actual explosive damage. The Sheltering Module would prevent the player from self-damaging. The Cluster Launcher is a very interesting weapon because it's a rather powerful weapon (low RoF, though) but dangerous to use because of the potential self-damages. The combo with the Sheltering Module would be interesting, allowing the player to carelessly use it, more like a regular weapon, at the expense of the module and main weapon slot (changing either slot would make the other less interesting, thus the interest of a combo).
2) The Cluster Launcher could be an energy weapon. It's slow-firing and while it can damage player, it's unlikely to use it permanently, like a regular, free ammo weapon. Also, it would allow the use of sync-firing drones, such as the Corrosive Drone, without the fear of self-damaging because of the main gun.
What do you think? Have you looted the Cluster Launcher? Have you tried it? Don't you feel it being a primary weapon sounds odd?