It’s not hard to recover the combination to a combination lock. With three numbers ranging from 0 to 39 there are 64,000 possible combinations and attempting to brute force a solution at 10 seconds per try could take 22 days of non-stop testing. With this technique it will take only 15 minutes without any experience. After you’re successful, it takes less than 10 minutes to crack the combination. I’ve even included a program that will help narrow down the possibilities and make the process quick and painless.
This procedure was designed for Master Lock brand combination locks new and old. The illustration shown to the right illustrates the “slop” in the mechanics of the lock. A combination of 22-10-17 is the same as 22-11-17 or 22-9-17. This makes Master Lock combination recovery a lot easier.
Step 1. Make a list of possible last numbers of the combination.
- Turn the dial clockwise past zero three times and leave it set to zero.
- Apply even tension to the metal shackle (U-shaped part) by pulling down if it’s attached to something or pulling up if you’re holding it in your hand. This causes the dial to stick and not turn easily. So, apply just enough tension and turn the dial clockwise until it stops. Note whether it stops right on a number or between two numbers. While still applying tension turn the dial counter-clockwise (left) to find the range.
- If the range is between two numbers say 17 and 18, record the number as 17.5. If, on the other hand, the range is in the middle of two numbers, say 20.5 and 21.5 record the number as 21. This is the middle of the range. You can rest between numbers; it won’t affect the solution.
- You can release some tension from the shackle to get past the sticking point to find the next sticking point. Repeat this process until you get to zero.
HINT: The dial should stick every 3-4 numbers.
Step 2. Find the last number of the combination.
In one complete turn of the dial you should have 12 numbers recorded. 7 of the numbers should be fractions ending in .5 – these can be eliminated. Of the remaining 5 the last number in the combination is the whole number with the unique ending. For example, with my test lock I listed the following numbers:
38, 34.5, 31, 27.5, 24.5, 21, 17.5, 14.5, 11, 7.5, 4.5, 1. removing the fractions and the similar numbers ending in 1 leaves 38, the only number ending in something other than 1.
Step 3. Calculate the possible combinations.
Select the number you found in Step 2 into the Combination Calculator. It will calculate all the possible combinations, 64 in total, much fewer than 64,000, and it usually takes, on average, only 32 tries to find the correct combination.
Hint: And in case you forgot, it’s always twice past zero turning clockwise (right) to the first number, once past zero to the second number counter-clockwise (left), and finally clockwise (right again) to the last number.