I think part (a substantial part) of the American style gun is the American preoccupation with "magnumitis". Americans insist in asking a given gauge to do the job of the next bigger gauge. And of course an overloaded gun must be over weight to keep the recoil managable. This allows beavertails and the like to be used with out any weight penalty. For myself, most of my double guns are in the British style and I don't use 3 inch loads.