Taking off from where I left off in Reply #5:
A couple of quotes from African Hunter Magazine provide a foundation for some of the later conclusions:
“The only area that Taylor considered the 9,3x62 unsuitable for was following up wounded elephant in thick cover, and most hunters would agree. The penetration is there aplenty, enabling the bullet to reach the vitals from any angle, but the sheer bullet energy needed to turn a close quarters charge just simply isn't there (nor is it in the .375 H&H for that matter). Nevertheless the 9,3x62 found immediate acceptance amongst even the large-bore fans in the professional elephant hunting fraternity, for use in open country where shots over 20 meters were the norm. In thick bush, or when following up a wounded elephant, the professional would then take his heavy rifle (a .500, .505 or larger). In truth, many of the small-bore fans kept at least a .450 double in reserve for wounded jumbo in the thick stuff. Wounded elephant aside, the 9,3x62 adequately fitted the bill for everything else.”
“George Rushby favoured his 9,3 double for both elephant control work and for shooting lion. Ten of the man-eaters of Njombe fell to George's 9,3, and he records with sorrow how he was forced to sell the 9,3 for financial reasons and purchase a .400 which, although just as effective on elephant lacked the "shocking power" on the big cats. This of course was simply a matter of velocity as the 9,3' s velocity is above the critical velocity at which explosive wounds occur in flesh (2200-2250fps), and so the bullets tend to produce a much more extensive wound and "shock" to the central nervous system than the larger, slower bullets.”
To condense several years of study and some actual hunting experience of my own (admittedly not a statistically significant sample i.e. < 10 head of deer, antelope, and elk): In order to get quick results an initial flesh velocity of Mach 2 or higher with a Sectional Density of 0.3 or higher will provide complete penetration and significant shock.
To summarize this from the performance of the 9.3x62mm a 286 grain has a Sectional Density of 0.305 lbs/in^2 and a muzzle velocity of 2,380 fps. What makes this “the easiest shooting major caliber” is a bullet weight that has the “magic” (i.e. Threshold) Sectional Density > 0.3 and stays above Mach 2 out to 80 yards.