you calculate bullet energy with the following formula
bullet weight in grains x velocity x velocity at impact, velocity ,divided by 450240= ft lbs
Id point out there's a compromise in every choice made, as long as the average projectile used in the handgun the cartridge is chambered for,
has the potential to punch through to and destroy the vital internal organs at any reasonable range or angle ,
that your reasonably expected to use that handgun & cartridge at, to accomplish the job at hand,
the cartridge should be adequate for the job its intended to handle.
with the 45 acp cartridge, was intended to be used by the military, so that opponent or threat would generally considered to be full size male adult at under about 70 yards
a 45 acp with its 230 grain hard ball at near 800 fps or similar hollow point has a decent historical record of doing just that!
the 44 mag is generally considered to be used with a 240 gain bullet at maybe 1300 fps from a 6" revolver will easily handle deer and hogs at 100 yards , and certainly more than adequate at shorter ranges for stopping social delinquent's/ criminal deviants, meaning you physical harm.