How to Open Hardened Combination Locks

Written by michelle labbe
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How to Open Hardened Combination Locks
Combination locks with a number wheel can be hacked eventually. (Combination Lock image by Mario Ragsac Jr. from

Hardened combination locks are designed to be more difficult to force open than regular combination locks. They feature shackles of hardened steel that are resistant to standard lock-picking methods. This is excellent as a deterrent to thieves and burglars, but not so helpful if you forget the combination and need to pick the lock yourself. If you urgently need to open a hardened combination lock, however, there's an alternative method to using a lockpick. With a few expert techniques, you can figure out the combination without spending hundreds of hours trying each and every number.

Skill level:

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  1. 1

    Begin spinning the combination wheel counterclockwise. You're going to start with figuring out the last number, and work your way backwards. Pull up on the latch as you rotate the dial. When you feel the hinge inside lock, write down the number on the dial and keep spinning. Some numbers will be decimals between two numbers, such as 12.5 or 17.5. You should end up with 12 numbers total.

  2. 2

    Cross out the numbers with a decimal point, leaving only the whole numbers. You should have 5 numbers remaining on your list. Four of these numbers should end in the same digit. Cross these out. The remaining number is the correct last number in the combination sequence.

  3. 3

    Calculate your options for the first and second numbers systematically. A trick of combination locks is that you can be off by a digit or two for the first two numbers in the combination. Narrow your options by choosing all odd numbers or all even numbers. This will allow you to be a little off but still able to open the lock.

  4. 4

    Spin the dial through your possible choices for the first and second numbers, always ending with the third number you calculated, until the lock opens. Write down the full combination for future use, or reset it.

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