Hydrostatic Shock
A debated terminal effect in which a fast bullet's pressure wave is said to damage tissue beyond the physical wound channel.
Hydrostatic shock is the proposed idea that a high-velocity bullet sends a pressure wave through fluid-rich tissue, causing injury at a distance from the actual hole the bullet cuts. Proponents argue this remote effect helps explain rapid incapacitation from some kinetic energy heavy loads, while skeptics hold that the crush and stretch of the permanent and temporary cavities account for the observed damage. The topic remains genuinely contested in the wound-ballistics literature, and you will find credentialed researchers on both sides.
For practical terminal ballistics the safer planning assumption is that reliable penetration and controlled expansion do the work, since those mechanisms are well documented and repeatable. Treating hydrostatic shock as a bonus rather than a design goal keeps your bullet selection grounded in effects you can count on. It is worth understanding the debate without overstating either claim.