An inexpensive pair of industrial grade or general purpose bolt cutters should break open a Master padlock. According to Homesessive, to crack the code to a combination Master lock without the use of tools simply follow four steps:
Step one: Push up on the clamp. Hold it in place. Spin right until a click is heard. Step two: Move two numbers to the right to get the first number. Step three: While still holding the clamp up, spin left until it stops to get the second number. Step four: Spin right. It will be very choppy, but keep the clamp up. It should open on the third number. This method takes about 12 seconds and preserves the lock for future use.
An alternative way to break a Master padlock is by shimming it using an aluminum soda can. According to Imminent Threat Solutions, shimming a single or a double-lock Master padlock is essentially the same, but with the double, two shims are used. This works by inserting the shim into the space between the padlock body and the shackle, on the side opposite the shackle’s locking grove. Once inserted, turn the shim while working the shackle up and down. This allows the shackle to almost pull the shim into the locking mechanism as it is being turned. The shim acts as a bypass by moving the locking mechanism out of the way, opening the lock. On the double-lock Master padlock, both sides of the shackle must be disengaged to open both locks.