I guess I feel that the differance is easy to understand and hard to explain.
A .270 bullet applied to the proper places at 3000 FPS induces hydrostatic shock.
A 45 cal bullet that opens properly or a 54 cal ball of pure lead at 2000 FPS induces about the same amount of hydrostatic shock when applied to the same place.
Now how many people understand hydrostatic shock?
My version of it, when you hit the knot of arteries and veins right over the top of the heart the shock wave travels through the blood the same as the pressure travels through the break system of a car when you stomp the brakes, only in an animal when it is done right it jellies the brain and the animal drops right there. No blood trail needed.
The key to getting this kind of a result is careful shot placement, if you get both lungs the distance the animal will go is limited but if you don't hit the right area it will run, and the best bullet helps but is not a cure all, no matter how good the bullet is it can not do its job in the wrong location.
So the combination of velocity, caliber. bullet action,shot placement, and enegry level to get the best results.
I think my self the .270 at 3000and the .54 caliber PRB are a good demonstration of that, because only certain .45 cal bullets give an equal comparison. The .40 cal is not to be overlooked either at 2200 it can give excellant results. Hope this helps. And I wonder just how many will disagree with me on this. Lee