Your bet bet is taking either a Skitari-Vanaheim shotgun or, if your GM thinks it's okay, that monstrous Arbites Shotgun from Book of Judgement. Whichever you take, remember to add the fire selector - shotguns' greatest strength lies in ammo versatility. Adding either the Exterminator or an attachable grenade launcher (or both, as technically they're not exclusive) will further improve the number of options you have.
If you're really dead set on making a two pistol build, ask the GM to let you buy the necessary Talents earlier as elite advancements.
There is no truth in flesh, only betrayal.
There is no strenght in flesh, only weakness.
There is no constancy in flesh, only decay.
There is no certainty in flesh but death.