High Dex melee build, dump Perception, Versatility for Guns skill. Pneumatic ancient rathound gloves for the power fist, so you'll need Tailoring and Mechanics, at a bare minimum. 44 Hammerer for your big bore pistol. You'll be looking at getting to 12 attacks per round, so you can end the combat turn with a pneumatic + combo strike for heavy damage. That'll be easier with psi haste, but if you don't want to be a heretic to the corpse god then you might want to consider 10 Agi for Blitz. Either way, you're going to want 14 Dex plus tabis so you can easily get you attack AP down to 7.