A friend who was licensed taught me years ago, I have my own pick set and a puzzle of really hard locks. While I see the advantage of using a bump, I think it defeats the purpose if you see picking as a puzzle, which is how I approach it. I'd love to learn safe cracking. This is a great book http://www.amazon.com/Secrets-Lock-Picking-Steven-Hampton/dp/0873644239/ref=sr_1_9?ie=UTF8&s=books&qid=1279869016&sr=8-9