Hollow-point bullet

A bullet with a cavity or opening in its nose, designed to expand on impact. Expansion increases its diameter and can reduce penetration beyond the target.

Bullet expansion: The deformation of a bullet that increases its diameter after impact. The intended effect of a hollow-point bullet is to expand as it enters a target.
Personal defense: Measures and practices intended to protect individuals from physical harm. Hollow points are commonly chosen for defensive handguns because expansion can limit overpenetration.
Full metal jacket: A bullet whose metal jacket covers its nose and usually limits expansion on impact. Its covered nose contrasts with the exposed cavity that defines a hollow point.
FBI penetration standards: A set of ballistic-test criteria used by the FBI to evaluate handgun ammunition, including penetration in gelatin. These tests make penetration depth a measurable design criterion alongside expansion.
Jacketed hollow-point: A hollow-point bullet with a metal jacket surrounding part of its softer core. Its jacket and exposed cavity shape how the bullet deforms on impact.
Hunting bullet: A projectile designed to penetrate an animal and cause sufficient tissue damage for a humane harvest. Many hunting bullets use expanding designs, including open-tip forms.
Soft-point bullet: A jacketed bullet with exposed soft core material at its nose, designed to expand on impact. It expands through an exposed core rather than the hollow nose typical of a hollow point.
Barrier-blind ammunition: Ammunition engineered to retain useful performance after passing through common barriers. Barriers can clog hollow-point cavities and prevent the intended expansion.
Ballistic gelatin: A calibrated gelatin medium used to study projectile penetration and deformation. Gelatin tests reveal how far hollow points penetrate and whether they expand.
Overpenetration: Projectile passage through a target with enough remaining energy to continue beyond it. Reducing the chance of passing through a target is a central reason for choosing expanding bullets.

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Armor-piercing bulletCompared with: Expansion favors wound formation rather than resisting deformation to penetrate armor.