i. Pin states
A false set can be particularly deceptive to a novice lock picker. To understand a false set, you must understand the states a pin stack can be in. There are only five possible states any pin stack can be in at any time, and only three of them are relevant during the picking process.
The five states can be described as:
1. At rest: The pins are sitting in their natural position with the key pin resting in the keyway and the driver pin crossing the shear line. This is the normal state of a lock when no key is inserted.
2. Under-set: The driver pin is binding and has been lifted, but it has not yet cleared the shear line.
3. Over-set: The pin stack has been lifted too high and the key pin is now binding and crossing the shear line.
4. Set – The pin stack has been lifted to the shear line. The driver pin rests above the shear line in the bible, and the key pin is free to fall back into the keyway, not under spring tension.
5. Over-lifted: Both the key pin and bottom pin have fully cleared the shear line. This state is highly unlikely – nor desirable – in the picking process, but will be described in full in a later section on the Comb Attack.
While lifting a binding pin, any point in the action before the driver pin has crossed the shear line is considered under-set. This can be very deceptive because the pin stack will still behave very much like it is set, in that the key pin is able to free-fall into the keyway. You will know that a pin is under-set if no other pin in the lock will bind and each remaining (unset) pin stack is at rest. To overcome this, try going over each of the pins you have set up to this point and applying a minimal amount of additional pressure to lift the pin further. If the pin stack seems stuck, move on to another pin stack that you have already set. If all of the set pin stacks seem set, try reducing your tension slightly and lifting each of the set pin stacks again until you feel the under-set pin reach the shear line.
This state occurs when you have lifted a pin stack too high. It is relatively easy to detect because the key pin will be in a binding state and will be unable to fall back into the keyway. If this occurs, you can try easing off the tension very slightly to allow the pin stack to drop, though this will often result in resetting other pins stacks and you will have to start your picking process over
It is common in a high/low bitting to find yourself with false sets, and only practice will teach you how to overcome these pins states. If you find you are constantly setting a deep pin stack too high while trying to set a shallow pin stack behind it, try using a deeper hook. If you find yourself over-setting pins in general, you may wish to try using less force with your pick tool. If you find you have a tendency to under-set pins, you may wish to try lightening up your tension or using slightly more force with your pick tool, and pay attention to the noticeable click when a pin sets at the shear line.