Originally Posted by purehavoc
I wonder if the 10mm got that much penetration because it did not expand ? For personal defense ammo I would rather have the expansion of the 9mm
That is exactly correct. These tests are not intended as any sort of direct comparison. 10mm performs very well when a proper load is chosen. It is capable of penetrating very deeply with heavy solids or very shallow penetration with high velocity JHP or anything in between. It is analogous to the .357 mag in terms of energy. According to Dr. Fackler and Dr. Roberts a projectile needs to impact at a minimum of 2,000 fps for temporary stretch cavity to become a substantial wounding factor. For that reason, 10mm doesn't theoretically have any greater ability to stop a person than .40 S&W. Nevertheless, it is hard to escape the feeling that something
must be going on with all that extra energy. Look how hard that 10mm wallops the block in the test below. I mean, if there really were nothing to the idea that extra energy can contribute to stopping a person, then there should be no substantive difference in the ability of a 9mm 124 gr standard pressure and a .357 mag 125 gr to incapacitate.