Lock Bumping Keys

This question was rarely asked until just a few short years ago. With the proliferated knowledge of the existence of bump keys, however, many people now want to know the answer. The function of a bump key is obvious: bypass a tumbler lock. To actually understand how it works, one must first understand the basics of a tumbler lock.

A tumbler lock is the standard type of lock found on most businesses and homes today. It is crafted to accept a key with certain dimensions into its entryway. In the industry, this is called simply “keyhole.” What happens within the tumbler mechanism, however, is a series of pins of varied sizes move back and forth. In one position, these pins will prevent the rotation of the actual bolt or rod that the lock relies upon. In the unlocked position, the pins move slightly to allow movement to one side or another and thus disengage the actual locking mechanism.

A bump key is designed to work alongside these principles, rather than against them. The bump key is one that fits into a keyhole and has typically been cut to the deepest specifications permitted by the manufacturer. What this does is allow the bump key to depress every pin within the lock. This will not open the lock, however. Either by jiggling the key, or most commonly by striking the key with an object such as a mallet or other tool, the bump key temporarily jars the pins to allow the locking rod to then move and open. Some styles of locks require that they bump key be fully inserted and then withdrawn a step before the strike or “bump” takes place. With a well-crafted bump key and a skilled handler, this can be done in less than a second with minimal noise. Even clumsy bump key users, if they have the proper bump key, can usually bypass the locking mechanism within seconds. Sometimes, this causes a fair amount of attention to be drawn due to the multiple strikes required to unsettle the pins properly.

The use of a bump key can be virtually undetectable. If done properly, a bump key only temporarily dislocates the tumbler’s pins, allowing them to fall back in place once the lock has been engaged. In other cases, the bump key can permanently dislodge the tumbler pins, rendering the invasion obvious and the lock useless.

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