This is really the only option: (object in picture shown actual size.. sry about that, posting from phone)
Be wary of advice given by sales people at a lot of gunshops.. Even among the gun enthusiasts posting in this thread there is a bit of bad information.. for instance, spread out of a 18.5" 12ga shotgun barrel shooting buckshot down the longest hallway in your home is going to be about as large as your fist.
I sincerely suggest shooting with someone who knows their stuff before you make a purchase, knowing how to properly handle a gun and understanding recoil, etc will greatly impact the purchase you decide on.