I also was under the impression the faster you can shoot a solid the better, however this is not the case.
You are right with your explanation but only to a point. This is called "super cavitation".
Super cavitation is the use of cavitation effects to create a large bubble of gas inside a liquid, allowing an object to travel at great speed through the liquid by being wholly enveloped by the bubble. The cavity (i.e., the bubble) reduces the drag on the object and precisely this makes super cavitation an attractive technology. In super cavitation, the small gas bubbles produced by cavitation expand and combine to form one large, stable, and predictable bubble around the supercavitating object. The bubble is longer than the object, so only the leading edge of the object actually contacts the aqueous medium. The rest of the object is surrounded by low-pressure water vapor. A supercavitating body has extremely low drag, because its skin friction almost disappears. Instead of being encased in water, it is surrounded by the water vapor in the super cavity, which has much lower viscosity and density. A super cavity can also be formed around a specially designed projectile. The key is creating a zone of low pressure around the entire object by carefully shaping the nose and firing the projectile at a sufficiently high velocity. At high velocity, water flows off the edge of the nose with a speed and angle that prevent it from wrapping around the surface of the projectile, producing a low-pressure bubble around the object. With an appropriate nose shape, the entire projectile may reside in a vapor cavity.
However, once you exceed a certain velocity(depending on caliber). For DG cartridges this velocity is about 2400fps, after that they penetrate less. Without getting too technical, the bullet basically starts overtaking the Cavity it creates and penetration is greatly reduced. Lots of info on net.
Let me just say if you have a heavy for caliber bullet(or call it normal for caliber if you like), 400gr for 404 Jeff, 410gr for 416 Rigby, 570gr for 500 Jeff and you are using either a premium bonded bullet or a Meplat monolithic solid you will have all the penetration you need for all the animals you could hunt in Africa.
If the heavy bullet gives you the optimum performance why would we need to change?
Sure you get the lighter bullet higher velocity bullet followers and then you get my type, the old school heavy for caliber at the optimum velocity followers. I will stick to heavy for caliber bullets at 2300FPS in my DG rifles as they have never let me down.
