Groo here
What few remember is that when the jhp bullets first came out,[supervel]
one of the biggest selling points was reduced ricochet ,bounce back,
and over penetration.
The "stopping power" aka "slap " as Keith would say, is generated
not by the damage inside but by the pain on the outside.
The modern HP has a wound like a hunting bullet , the game may run
off but die quickly.
What we want is just the opposit.
We want the target to STOP,,, the die quickly part dose us little good in a fight.
A stop is generated by the stopping of the computer, by damage or
input [ aka pain]
Bleeding / shock can take between 8 to 30 seconds or more.
The pain is in the skin first then muscle , internal organs least and last.
This is why a large flat on the nose of a bullet , a larger buller, or
a jhp that opens very fast like the 125gr 357 with a lot of lead at the tip
work so well.
The nose does all the work as keith says, the physical impact that stuns
the target.
The hole in the organs keeps the game from running too far.