The common scientific tests for measuring the effectiveness of handguns for defensive applications are relatively simple, but humansare not. One popular test is to fire handgun cartridges into ballistic gelatin. This test meets the scientific requirements of creating measurable,repeatable results in a safe, controlled environment. These results are then used to estimate stopping power.
However, unlike a block of gelatin, the humanbody is a complicated organic machine composed of bone, skin, muscle and erratic chemical reactions. Add to this the likelihood that both the defender andthe assailant will be in motion during the conflict, and things start to get complicated. A particular ammunition choice may excel in lab tests, but ifshot placement is poor, or the shots miss altogether, then the round's inherent effectiveness becomes a moot point.
Of the factorsthat play a role in a gun fight, the mindset and attitude of the combatants is one of the most important, and the most mysterious. One report I readdescribed a person passing out and nearly dying of shock from a .22-caliber scratch on the arm. Another told of a government agent, after being shot five timesin the torso by handgun bullets, walking over to a medic and asking for assistance. What’s the difference between these two reports? There's an old sayingthat seems to sum up the psychology of a gun-fight quite nicely, “It’s not the size of the dog in the fight, but the size of the fight in the dog."