Just a little history, if my memory serves.
In 1986, in the infamous "Miami Shootout", an FBI Agent got a solid hit
on one of the badguys with a 115 grain Winchester Silvertip hollowpoint.
The hit was fatal, but not immediately incapacitating. As a result, the
FBI did a battery of ammunition tests with gelatin and a series of
Following this, the FBI switched to Federal Hydra-Shok 147 grain
hollowpoints. According to the tests, this round gave deeper
penetration through barriers than lighter weight bullets. Expansion was
less than lighter loads but the FBI decided that, due to the variety of
shots that an Agent might have to take - facing badguys behind doors,
windows, car doors, car windshields, walls, etc. - penetration was more
important. Much like European armies in the 1920s planning to re-fight
the First World War, the FBI found a round that would have performed
better during the Miami Shootout.
Does that mean that the 147 grain bullet is "better" than the 115 grain
Silvertip? Perhaps, for law enforcement officers needing to know their
bullets will penetrate car bodies and other obstacles, the answer is
"yes". For average citizens who will likely face criminals with no more
than clothing as a barrier, the answer is probably "no". Perhaps bonded
rounds are the best "solution" to the penetration equation, which allow
lighter weight (124 grain, 127 grain) rounds to penetrate more uniformly.
As the FBI found out, there are no "magic" bullets. Expansion is
ephemeral but penetration is forever. Hits are what counts, and shot
placement is paramount. Get multiple, solid hits on the badguy, and
hope he misses in all the excitement. Then hope your bullets do what
they are designed to do. I do not, by the way, think there is no value
in "near misses". The very fact that you are returning fire will cause
the badguy's accuracy level to drop significantly, hopefully leading him
to miss you.
Just some random thoughts....