So, I don't have names, rarities, etc. for this line, but here's what I'm thinking:

The primary fire would fire a strong concussive blast, similar to the Magnus' charge attack but with wider spread (about 1.5 times as wide as the knight maybe), much shorter range (like 4-5 tiles max) and much greater knockback, capable of sending most foes flying across the room. Like the magnus, it would only be able to fire two shots before needing to reload.

the charge attack would probably be a more powerful version of this, with more damage and knockback, enough to even move larger enemies like Lumbers a fair distance

Again like the magnus, it would likely have variants for the different damage types, and probably apply stun (you are launching them across the room, after all. There's bound to be a concussion or something)

All in all, great as a tool for pushing foes back, whether to herd them into a corner for a brutal combo attack, or to get out of being surrounded, as well as being a decent damage dealer, especially against stationary enemies like gun puppies, howlitzers, and battlepods