The problem isn't necessarily with the shotguns, although their range needs toned down for sure as do fusion rifles. The problem is they need to nerf the fucking RADAR.
Being able to know exactly where an opponent is, and even relatively how close to you he is (radar slice turns dark when he's close, circle turns red when you're nearly on top of him), makes it pretty damn easy for shotgun cheesers to just round a corner and pull the trigger without actually looking for you, hitting you square in the chest 90% of the time.
Radar needs to be switched to motion detector, not friggin know-where-everyone-is the way it currently stands.