Stakeout

While many prefer the silenced SPAS the Stakeout is a much better decision if your going for a shotgun. Here is how the class would look

Primary Stakeout
Attachment Grip
Secondary Crossbow
Lethal Semtex
Tactical Concussion
Equipment Motion sensor
Perk1 Lightweight pro
Perk2 Sleight of Hand pro
Perk3 Ninja pro

With Lightweight, Sleight Of Hand and Ninja you'll be a fast, quick reloading, silent assassin. Even tho this class is mostly based on close range combat, the added crossbow let's you still get those long distance kills. The motion sensor will help you find easy kills near by you. Whether your running around or camping this is the best shotgun class.