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What Is a Bump Key and How Is it Used?

Lock picking has been around for centuries, and while it may conjure up images of skilled thieves silently breaking into homes, the truth is that lock picking techniques are often used by locksmiths and law enforcement for legitimate purposes. One such technique is the use of a bump key. In this article, we will explore what a bump key is and how it is used.

Understanding the Bump Key

A bump key is a specially modified key that can be used to open pin tumbler locks. Pin tumbler locks are the most common type of lock, found in residential homes, offices, and even cars. These locks work by using pins of different lengths to prevent the lock from opening unless the correct key is inserted. A bump key exploits the mechanical nature of pin tumbler locks, allowing it to bypass the need for the correct key.

How Does a Bump Key Work?

To understand how a bump key works, we need to first understand how pin tumbler locks operate. Inside the lock, there are a series of pins that are divided into pairs. Each pair consists of a driver pin and a key pin. When the correct key is inserted into the lock, the key pins and driver pins align at the shear line, allowing the lock to turn and open.

A bump key, on the other hand, is designed to mimic the shape of a correctly cut key. The key pins inside the lock are pushed up by the bump key, and then the key is struck sharply with a hammer or another object. This causes the driver pins to jump momentarily above the shear line, allowing the lock to be turned and opened.

The Advantages and Disadvantages of Bump Keys

Bump keys have both advantages and disadvantages. One of the main advantages is their simplicity. Unlike other lock picking methods that require specialized tools and training, bump keys can be easily made using regular keys. This makes it a popular technique among locksmiths and law enforcement, as it allows them to quickly gain access to locked doors without causing damage.

However, the simplicity of bump keys is also a disadvantage. Since bump keys can be easily made, they can also be easily obtained by individuals with malicious intent. This has led to concerns about the security of pin tumbler locks. In response, lock manufacturers have developed bump-resistant locks that are designed to be more resistant to bumping techniques.

The Legality of Bump Keys

The legality of owning and using bump keys varies from country to country and even within different states or regions. In some places, it is illegal to possess a bump key unless you are a licensed locksmith or law enforcement officer. In other places, bump keys are considered legal as long as they are not used for illegal purposes.


Bump keys are a fascinating tool that can be used to open pin tumbler locks. While they have legitimate uses for locksmiths and law enforcement, there are also concerns about their potential for misuse. As lock manufacturers continue to develop more secure locks, the future of bump keys remains uncertain. Whether they will become obsolete or continue to be a part of the lock picking arsenal, only time will tell.