Buying A Bump Proof Lock
The easiest way to protect yourself is to use a lock that does not use a pin tumbler. Most mortice locks use levers and do not use pins on springs so are bump proof by design. We recommend British Standard Mortice Deadlocks. You can check if your mortice lock is British Standard by looking for the Kitemark.
The first step in bumping a lock is creating a bump key for that lock. To create a bump key you need a key which has the correct profile to fit into the lock i.e it needs to be able to fit into the lock. The more popular and widely available your lock - the greater the chance a bump key can be easily created. If your lock has a restricted key profile or a very uncommon profile it will harder to create a bump key. This will offer some protection against having your lock bumped but it may still be possible to manufacture a key with the correct profile. So a restricted key profile alone may make a lock harder to bump but does not make a lock bump proof.
Many rim locks are vulnerable to bumping because they use pin tumblers. Some however use a different mechanism, like the Union 4L67E British Standard Rim Deadbolt. This lock uses discs instead of pins and so cannot be bumped.
Some locks that utilise pin tumblers also contain additional security elements such as a sidebar. These elements may significantly reduce the risk of bumping, as although the pin tumblers can be bumped the sidebar would frustrate or prevent a bumping attack.
There are a few very secure cylinders that don't make use of pin tumblers at all. For example the Evva 3KS Plus cylinder uses sliders and sidebars with no springs so can be considered bump proof by design.
It may be possible to upgrade the cylinder in your lock to one that is very hard or virtually impossible to bump. Many cylinders found in door locks are fairly easy to remove and replace and can be done on a DIY basis :-
uPVC Doors: Many Euro profile cylinders found on uPVC doors are vulnerable to bumping and should be upgraded. Often this cylinder is the only lock controlling all the bolts on the door so it is very important it is secure. There is a single screw on the edge of the door that retains the cylinder that needs to be removed. Then the key needs be inserted and turned a quarter turn to align the cam and the cylinder can be pulled out the door.
Rim Locks: Most rim locks have a common rim cylinder on the outside of the door that can be easily upgraded. The outside cylinder can be remove by removing the lock and undoing the two screws which hold it in place. Some rim locks also have a cylinder on the inside. These are often built into a handle and are not easily upgraded.