[O.B.Left]

a feathery? Is that an old type of golf ball? Filled with feathers?

If I were to guess, I would guess that hinge action makes the biggest difference on balls with a high rebound factor (whatever that might be I guess you can call it Coefficient of Restitution)

But say you have two balls: One filled with sand, the other a Pinnacle made for max distance. You drop both to the floor. The floor will provide a close to perfect compression situation. The sand ball will just adopt the speed of the floor which is zero. Drop and stop. The Pinnacle will bounce back almost to the same height as you dropped it from. If the Pinnacle ball for some reason were rotated while it were in contact with the floor, so the line of compression were shifting during the impact interval, the ball would bounce less. But the ball with sand would behave the same.

Soap the floor .... spin the ball before you let it drop .... this may actually be testable. You might need to spin it really fast though.

There may be other factors of course that complicate things.

Thank you Doctor.