Hollow point bullets are a type of ammunition designed with a hollowed-out shape at the tip. This design allows the bullet to expand upon impact, creating a larger wound channel. The primary purpose of hollow point bullets is to increase stopping power while minimizing the risk of over-penetration, making them popular for self-defense and law enforcement use. When a hollow point bullet strikes a target, the hollow cavity fills with tissue or fluid, causing the bullet to expand. This expansion can lead to more effective energy transfer and reduced risk of injury to bystanders, as the bullet is less likely to pass through the target.