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How to bump a lock
Start with an ordinary key.
Find a key that fits into the lock you're attempting to bump. The teeth of the key won't be the right size or dimension to move the pins, so the key won't turn, but it's important that it be able to slide inside.
Locks and keys come in all different makes, but many keys will fit into a standard cylindrical home lock. If you're fashioning your own bump key, pick a key that you don't use regularly.