Bump key

A bump key is a key prepared to open some lock cylinders by impact without breaking them, taking advantage of the way they are built inside. It is a well known technique, which is why many manufacturers design their cylinders to resist it.

What makes it dangerous is that it leaves hardly any trace. The door opens with no damage and often nobody can work out how the burglars got in. Sometimes you can see small knock marks on the face of the cylinder, or the key starts to feel different.

The defence is a cylinder with anti-bump protection, which usually comes together with protection against picking, drilling and snapping. If the one on your front door is basic, especially in a home that stands empty for long periods, it is worth changing the lock cylinder for one that resists it.