The 'Magnus effect', what we know as hop up, does two things: 1/ It generates lift on the lower front of the BB; 2/ It reduces the drag behind the BB, same as having a boattail bullet. Both of those is what makes the BB fly farther and straighter than if there wasn't any hop up.
I see where Cactus is coming from, he's suggesting more mass near the surface of the BB, getting the centrifugal force to make the BB spin more consistantly and longer. Unfortunately, velocity drops of rather quickly, and is hard to keep the momentum for increased range.
Way I see a BB's flight, you break it into three parts (call them thirds): 1/ The pure velocity coming out of the barrel, where hop up doesn't do anything and BB is the most resistant to air currents; 2/ The reduced velocity where the hop up does it's thing, still has speed and a decent resistance to air currents; 3/ The section of flight where velocity is so greatly reduced, hop up doesn't have as much of an effect anymore and the BB strays/becomes more susceptable to slight differences in air. All of the above just about every player has seen when shooting and watching the BB's flight path, if they actually WATCH what a BB does. Snipers are at top of the list for this, because we have to compensate for for where the previous BB went, based upon the air patterns in our area of shooting. It's really not something that can be predicted, not accurately, it's literally a test shot then the real shot.
Overall, I doubt a hollow BB with the same weight would make any difference, but it is a very neat concept though.