Hollow-point

A hollow-point bullet is an expanding bullet that has a pit or hollowed out shape in its tip often intended to cause the bullet to expand upon entering a target in order to decrease penetration and disrupt more tissue as it travels through the target. It is also used for controlled penetration, where over-penetration could cause collateral damage (such as aboard an aircraft). In target shooting, they are used for greater accuracy and reduction of smoke, fouling, and lead vapor exposure, as hollow point bullets have an enclosed base while traditional bullets have an exposed lead base.

Hollow points are designed to increase in diameter once within the target, thus maximizing tissue damage and blood loss or shock, and to remain inside the target, thereby transferring all of the kinetic energy to the target (whereas some fraction would remain in the bullet if it passed through instead). Both of these goals are meant to maximize stopping power. Jacketed hollow points (JHPs) or plated hollow points are covered in a coating of harder metal (usually a copper alloy or copper coated steel) to increase bullet strength and to prevent fouling the barrel with lead stripped from the bullet. The term hollow-cavity bullet is used to describe a hollow point where the hollow is unusually large, sometimes dominating the volume of the bullet, and causes extreme expansion or fragmentation on impact.

Plastic-tipped bullets are a type of (rifle) bullet meant to confer the aerodynamic advantage of the spitzer bullet (for example, see very-low-drag bullet) and the stopping power of hollow point bullets.

...
Wikipedia