just a thought on a couple of weapons....
maybe a grenade launcher + assault gun (possibly researched) like an m203, perhaps based on a metalstorm design (google it) so you can fire 1 round, or up to 3 rounds before a reload is required, it would have a smaller blast radius than the regular grenade launcher, but has the bonus of being an assault gun.
a railgun....you would research it of course.
