Read this this morning and came here to post it before I got side-tracked
It talks about how we can't really quantify how much energy is transferred to game by various bullets, which is one of the reason all the usual topics - SD, energy, velocity, caliber - are limited in terms of describing 'killing power'. Worth a read, IMO.
http://www.rifleshootermag.com/ammo/...pound-fallacy/
Even talks about the 45-70 and 30-30 and why these relatively unimpressive rounds (from a velocity and trajectory POV), can be such reliable and impressive hunting cartridges. I don't own any rifles in these thumper cartridges, but for certain uses they make a lot of sense even though they are pretty much the antithesis of the high velocity, high BC, efficient cartridges.