... Longer might have an edge for crossing shots, but if both guns are balanced at the same point what's the advantage of one over the other?
I think the difference (some call it an advantage) is that longer barrels, even if balanced exactly the same as shorter, will have a different moment of inertia and will therefore both acquire and shed momentum more slowly than shorter barrels. That is, the longer barrels will take longer to get moving and will keep moving in a swing when shorter barrels could and would stop. Balance fore and aft is one thing, momentum in swinging the gun, another.
Not necessarily so, Dave. I have shot a Valmet O/U, that belongs to a close friend, that has 36" "waterfowl" barrels. They are so well struck and balanced (don't even have a top rib) that you would think you were shooting a good handling 30" Perazzi. They are absolutely amazing to swing, and are equally so to look at. The look more like 16 ga. than 12 ga., which is what they are.
You just can't say that long barrels are harder to get moving and harder to stop. It's all in where the weight is deposited in the gun. or, as Don describes it, the compactness of the gun.
JMO, SRH
