As a matter of fact, even Ken Waters got 2,400fps with 400gr. in the Ruger factory test 1-up rifle, and his loadings are usually kept softer than most people load. If Ken can do it, anyone can. That was before some of the new extreme powders (and others), which makes that velocity even easier - at pressure not higher than factory magnum pressures of 63,000PSI.
: I know darn well the .416 Taylor will make 2,400fps with 400gr. bullets. John Whooters was also able to get it, and used that loading very successfully in Africa for several years as did other hunters back in the 50's through 70's.
; The fact that a larger case will do it with less pressure means squat. Of course a larger case will do it with less pressure - that's plain physics. That the smaller case will do it, is also plain physics.