For many years, Locksmith Professionals have utilized several methods and tools to bypass pin and tumbler locks for legal purposes. One such technique is called “bumping.” Lock bumping, also referred to as key bumping is an attack technique using specially cut keys that can defeat conventional pin and tumbler locks. There’s nothing new about this but the Internet, in part, has popularized the subject. In fact, according to a Wikipedia entry, “a US patent first appears in 1928 by H.R. Simpson called a ‘rapping’ or bump-key. Then, in the 1970s, locksmiths in Denmark shared a technique for knocking on a lock cylinder while applying slight pressure to the back of the lock plug. When the pins would jump inside of the cylinder, the plug would be able to slide out freely, thus enabling the locksmith to disassemble the lock quickly.”
Search “lock bumping” on the Internet, and you’ll find plenty of how-to videos to tell you how to do it. Here’s one that’s particularly informative and has some good graphics (just ignore the misspelling of “shear line”): http://youtu.be/7xkkS2p7SuQ
These days, several manufacturers make bump resistant and bump proof locks, but if you have an older lock, you’re vulnerable. Consider changing over to newer technology. Why? According to statistics provided by the National Crime Prevention Council (NCPC) and the Department of Justice, nearly 2/3 of all break-ins occur with no sign of forced entry. How many of these break-ins can be attributed to lock bumping is uncertain, but it’s a good bet that at least some of them are.