Crack a Master Lock – Mathematically, No Shim « Wonderment Blog.
Apparently it is possible to reduce 64,000 possible padlock combinations down to 100. From Mark Edward Campos, an incredibly clear How-To on cracking a master lock:
For an enlarged version, click here.
Looking for something a little more interactive? Loads of lock picking tutorial videos here.
Here’s a video that demonstrates the same method (math as opposed to shim):