Lock Bumping. Securing Doors And Windows In The Face Of Clever Criminals

October 7, 2023 0 Comments

By Ralph Winn

Security expert Marc Weber Tobias is worried about your front door .. . and your back door, your side door, your windows, and your garage door. His expertise focuses on securing doors and windows, and he knows about the most common threats to that security. One common security threat that has been on the rise since its discovery by locksmiths in Denmark in the 1970s is ‘lock bumping.’ As Tobias can tell you, securing doors and windows – and ultimately, your loved ones and valuables – takes more than the basic lock these days.

What is a ‘Bump’ Key?

A ‘bump’ key works by tricking the tumblers in a pin lock to fall into the correct place for just an instant, but long enough for someone to turn the key and unlock the door. A basic key, a sturdy file, a little pressure, and a gentle ‘bump’ against the key is enough to knock the pin tumblers into place and pop a lock open.

‘Any pin tumbler lock that utilizes two or more moving pins within each chamber is at risk. Door locks, post office locks, file cabinet locks, access control override locks, and padlocks. All of them can be bumped if you have the key that will fit the keyway and has been properly cut .. . Are there exceptions? Yes. Can every conventional lock be bumped open? No, but statistically, a very high percentage can,’ says Tobias in his online column ‘The Lockdown.’


Not only can a criminal easily get inside, but you may run into insurance troubles if there is no sign of forced entry. A ‘bump key’ leaves no marks or scratches. It looks as though someone had a key to unlock the door. They did, technically, have a key – a ‘universal’ key.

What can you do to ensure that you are properly securing doors and windows? You can install advanced, contemporary lock technology that has addressed the ‘bump’ key threat and made it irrelevant.

Securing Doors and Windows Against Bump Keys and Other Tricks

Fortunately, since the ‘bump’ trick was developed over 30 years ago, security companies have had time to come up with answers to the threat. If you have locks built before 2005, you might want to consider having them replaced with these more secure models:

Medco – In 2005, Medco introduced its response to the bump key problem by adding an innovation to the design of all of their locks. A piece known as the M3, included in all their models, is an additional pin that is not controlled by the grooves of the key, like a traditional pin, but by the forward motion of the key. A simple bump cannot cheat the M3 into unlocking position. The added level of security within the lock itself helps in securing doors and windows.

Schlage -The Schlage Primus model increases the complexity of a lock’s inner workings by adding a second set of pins along the side of the key that must also be properly manipulated to unlock the door.

Additionally, electronic locks, magnetic locks, and locks using rotating disks are not vulnerable to this ‘bump’ attack.

Extra Protection When Securing Doors and Windows

When you are at home, it’s a good idea to activate that second line of lock defense – the hidden deadbolt, which has no external keyhole. Even if someone bumps their way through the first lock, the hidden deadbolt will stop them long enough to make them give up. A criminal who wants the ease of a bump entry will probably not resort to crowbars and kicking once their bump attempt is blocked by a second lock.

Remarks Tobias: ‘Yes, locks do matter in protecting a residence. Many burglaries are crimes of opportunity. If the locks prevent bumping and that is the chosen method of attack, then the burglary may not occur.’

About the Author: Ralph Winn writes about

Security Systems

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