http://www.rossi-rifleman.com/viewtopic.php?f=32&t=571
Testing confirmed that in most instances the lighter Hollow Point (HP) projectiles (.380, 9mm, .40 cal.) open prematurely or do not open at all, the HP cup filling with target medium, turning itself into lighter ball ammo, or the HP projectile takes a different path from the flight path upon entering the target medium, resulting in non lethal hits or lesser wounds than intended due to deflection of the projectile from the unstable HP cup reacting to hydrostatic pressure from impact with the target medium (veering off course, so to speak).(2)
Heavier Ball ammo (any round of 200gr weight or greater) such as .45ACP 230 gr., .44 Special 246 gr., .45 LC 255 gr., .38 Special 200 gr. LRN,(3) all followed the intended flight path, even upon hitting bone. These projectiles gave the best observed handgun performance in creating damage that would be consistent with producing incapacitation of a human target with the fewest possible shots fired. They also did not exit the cadaver torso as the energy was invariably shed in the target, leaving no apparent energy for over-penetration and exit(4). Exit wounds did occur with face shots, head shots and extremities, face shots causing imparting of secondary velocity to teeth and chunks of bone, creating secondary fragment projectiles.