Shotguns are really fun on smaller maps, like Carrier or Hijacked (or Nuketown, of course). My "shotgun" class is the following:Remington w/ Long Barrel + Quick Draw (whatever that grip is called)No secondaryNo grenadesLightfoot + Hardline (will be Lightfoot + Ghost after a couple more levels)ToughnessDexterity + ConditioningI used to carry a betty, but I found that on the kinds of maps where I would run this class, it was always destroyed or I was always killed before it took anybody out, so I dropped my grenades for Hardline. The main thing though is that I can move as quickly as possible to wherever the enemy is without being in the open any longer than necessary. It's important to be able to close fast if you're going to rely on the shotgun.