ORIGINAL: Roskoe
I would agree that the "big bullet - modest velocity" guns of yesteryear cannot compare with today's high performance centerfire rifles. But the comparison is primarily related to the bullets travel from the muzzle to the animal, though. Once the bullet hits the vitals of a big game animal, it has been my experience that big bullets kill a lot better than their foot-pounds of energy figures would suggest.
Imagine the buffalo hunters of the late 1800's shooting these2,000 lb.beasts at 500 yards with abig lead bullet that only left the muzzle at 1200 fps. I'm not sure what the remaining energy is at 400 or 500 yards; but those big old bison were stacked up like cord wood with rifles in this peformance class. And bison are an animal that is known to scoff at a center chest hit with a 7 Rem Mag - look at the hunter as if to say "is that all you got?" Something to think about . . . .
Roskoe is absolutely correct about this. Although not a whole lot of buffalo shot with the old Sharps and Remington rifles just hit the ground and never moved again when those big ol' heavy bullets hit them, they usually didn't go very far, either.
I agree that "foot-pounds of energy" doesn't really do much to predict how well a bullet will kill something. As far as I have been able to determine, there really is no mathematical gyrations you can perform to find this out, either. The only really valid way of finding this out is by shooting things! And in this day & age, very few of us get the chance to shoot enough game to develop valid observations. Only people acting as professional hbunters or guides sget towitness enough game being killed to really learn much-guys like Les Bowman and Bob Hagel, for example. And even in this group, there aren't a lot of keen observers who pay enough attention to wound channels, bullet performance, etc., to form valid opinions!