My shotgun rules:
range 8" (1-finger cone), use 4, kills a standard minifig trooper on a D6 roll of 4+.
The nice thing about shotguns is that in addition to their standard attack you can stick a bunch of different specialized rounds in them, and it will automatically launch them 8". Things like grenades, Dragon's Breath rounds (which give the shotgun flamethrower stats for 1 attack), sensor units, and tazer rounds. Zombies killed by shotguns cannot come back to life.
Just one random act of violence can brighten your day. Especially if it involves explosives.