Hollow point bullets are bullets that have a small pit in their tips. This design allows the bullet to expand upon impact with a target, because pressure is generated inside the pit, essentially pulling the bullet apart. The use of these bullets is controversial in some communities, and there are a variety of arguments for and against the design.
A typical hollow point bullet is at least partially jacketed with a hard metal that will prevent the barrel of the gun from becoming fouled with lead. The jacket also helps maintain accuracy, with the hollow point further improving this by shifting the center of gravity to the rear of the bullet. When it hits a target, the bullet expands and the jacket falls away.
The primary advantage of these bullets is that they have increased stopping power. When one hits a target and expands, it causes significantly more damage than a conventional bullet, thereby bringing the target to a halt more quickly. In addition, overpenetration, a common problem with some bullets, is avoided, because the bullet slows radically when it hits.
People have been aware of the advantages of the hollow point design for a very long time, and for almost as long, people have debated the ethics of using it. Especially in countries that struggle with gun control laws, hollow points are sometimes a topic of controversy as people attempt to balance the desires of gun rights advocates with a genuine concern for safety.
From the point of view of law enforcement, hollow points are sometimes viewed as safer, because the risk of overpenetration and ricochet is reduced. When police are trying to handle a crowded situation, it can be helpful to know that if a police officer shoots hollow point bullets, bystanders are less likely to be harmed than they would if normal bullets were used. In addition, they neutralize a suspect more quickly, which can be critical in an emergency.
Some hunters also use hollow points to avoid the overpenetration and ricochet problem, and to ensure that they can kill big game animals humanely with one shot. These bullets are also used by some militaries.
Military use of hollow point bullets is actually banned under the Hague Convention of 1899, which prohibits the use of expanding bullets. Some individual communities have also banned the sale and use of hollow points, sometimes known as dum dums, arguing that individual civilians have no use for such bullets, and that the increased stopping power makes them a liability to law enforcement officers.