You might be right about this inertia thing, maybe, but personally I see no reason for the heavy barrels and heavy weight to begin with. All the 450's are only 5100 ft-lbs and needing an 11 -12 lb. rifle, as in the old days for sure, is just baloney. A kid could shoot those old clubs without getting hurt! Like a 450/400 I say advertised at Cabelas, almost 12 lbs. That can hardly be handy regardless of the weight distribuition.
Handy isn't really found until you get down to the small frame 375's and 9.3's, in the 8 lb. or less class. IMO.