in television and movies, and commonly referred to as "true stopping power" by uneducated proponents of large powerful calibers such as .44 Magnum, the effect of knockback from a handgun and indeed most personal weapons is largely a myth. The momentum of the so-called "manstopper" .45 ACP bullet is approximately that of a mass dropped from a height of . or that of a baseball. Such a force is simply incapable of arresting a running target's forward momentum. In addition, bullets are designed to penetrate instead of strike a blunt force blow, because, in penetrating, more severe tissue damage is done. A bullet with sufficient energy to knock down an assailant, such as a high-speed rifle bullet, would be more likely to instead pass straight through, while not transferring the full energy (in fact only a very small percentage of the full energy) of the bullet to the victim. Most energy from a fully stopped rifle round instead goes into formation of the temporary cavity and the destruction of both the round, the wound channel, and some of the surrounding tissues. There is no physical principle preventing a hypervelocity round from causing a splash injury in which the ejecta create rocket-like impulse on their way out to cause knockback, and indeed, no principle preventing a similar effect for exit wounds causing "knockforward", but this is still generally not anywhere near the impulse required to stop the motion of a sprinting person or knock them over from pure momentum. Sometimes "knockdown power" is a phrase used interchangeably with "knockback", while other times it's used interchangeably with "stopping power". The misuse and fluid meaning of these phrases have done their part in confusing the issue of stopping power. The ability of a bullet to "knock down" a metal or otherwise inanimate target falls under the category of momentum, as explained above, and has little correlation with stopping power. One-shot stop This hypothesis, promoted by Evan P. Marshall, is based on statistical analysis of actual shooting incidents from various reporting sources (typically police agencies). It is intended to be used as a unit of measurement and not as a tactical philosophy, as mistakenly believed by some. It considers the history of shooting incidents for a given factory ammunition load and compiles the percentage of "one-shot-stops" achieved with each specific ammunition load. That percentage is then intended to be used with other information to