Top 5 Destructive Methods to Bypass a Master Lock

Most common destructive lock attacks focus on cutting or drilling the lock allowing it to be easily removed from its fixture.  Although popular, these attacks are not always possible due to the presence of heat treated and hardened steels which limit the effectiveness of cutting tools.

While such common attacks are easy to defend against, with a little creativity you can find other vulnerabilities within the lock to force it open.  These vulnerabilities most often take advantage of moving parts within the lock or where two separate components interact, as these areas are much weaker than the reinforced steel of lock shackles.

Various attacks may be used to successfully bypass a lock, from freezing the lock to weaken its components or using explosives to shatter key areas.  Although there are some exceptions, this article focuses primarily on discrete bypassing methods that will draw the least attention to the attacker while being carried out.

Why focus on padlock attacks?

Each technique covered in this article work most effectively against padlocks, however in certain cases may be applicable to a wider range of locks.

Destructive techniques are most effective against padlocks because in most cases, you are attempting to damage the lock without harming the object it is securing.  This is entirely different from attacking house locks, as it is normally much easier to simply attack another vulnerability of the house (such as windows) than attacking the lock directly.

Additionally, many of the attacks that are most effective are not suitable for use against handcuffs because of the very different designs and construction methods.  

With that said, handcuff locks are much simpler than traditional locks making them much more vulnerable to picking attempts or key duplication (as handcuff keys are widely available online) making destructive attacks a waste of resources.

So, let’s have a look at how padlocks work to better understand where their vulnerabilities lie and how we may best take advantage of them.

Understanding basic padlock anatomy

Most common padlocks share a very basic design that goes back decades. While advances in lock security have been made, most changes have been to the materials used within padlocks or their construction methods instead of in the design itself.

Locks can be broken down into four basic components, being:

  • The body (also known as the shell or casing)
  • The core (the keyway and pin stacks)
  • The shackle
  • The locking bar
padlock anatomy

When the correct key is inserted, the driver pins are lifted from the core into the lock body, clearing the shear line and in turn allowing the core to rotate.  This rotation retracts the locking bar and allows the shackle to be removed from the body.  

Each element of the lock’s construction can be attacked individually, however the area where two elements interact is typically much weaker and is where we will focus almost all of our attacks explored here today.

#5 Spreading the shackle with wrenches

While many hardened steel shackles are resistant to cutting attacks, they are relatively weak to tension forces.  Using this information, it is possible to target the thinnest (and therefore weakest) part of the lock to cause the lock to open.

Two variants of this attack exist; however, one proves much more effective than the other.  

In the first technique, two wrenches are placed against each other parallel to the top of the lock body, so that when you push the handles of the wrench together the shackle is spread apart.

What makes this attack less effective is that while the lock is being spread apart, they are also attempting to push through the reinforced lock body which can severely restrict this technique.

Instead, a much more effective attack places one wrench parallel to lock body and another perpendicular to the previous wrench.  This prevents the lock body from impeding the attack and instead focuses the force on breaking the locking bar and allowing the shackle to come free of the lock.

This second attack is considerably more effective as internal components are not typically as reinforced or hardened when compared to external components as they are unlikely to experience many attacks.

In cases where the lock is reinforced, it may not be possible to generate enough force to open the lock, however on most common budget locks it is extremely effective and can be carried out in a matter of seconds.  

The biggest limitation of this attack is the space required between the shackle and lock body which in many cases prevents access of the wrenches and ultimately stop the attack from being carried out.

#4 Homemade jaws of life

In a similar manner to our previous technique, this attack takes advantage of the shackle’s relative weakness when under tension by attempting to spread the shackle until it eventually breaks and allows the lock to open.

This attack is relatively easy to construct and relies on two bolts and a long-threaded coupling nut.  The tool is assembled and placed inside the lock before rotating the coupling nut in order to force the bolts apart and force the lock open.

Graphical user interface, text, application

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What makes this attack so much more effective than prying the lock open with wrenches, or another tool such as a crowbar, is the coupling nuts ability to store energy. This allows you to build up much greater forces and almost guarantee an unlock, regardless of the strength or quality of the lock.

While effective, there are many limitations with this style of attack, namely in the size requirements.  As coupling nuts are typically at least two inches in length, it is not always possible to insert the tool into smaller padlocks.

Additionally, to support a range of larger lock sizes, you will often have to carry a range of bolt sizes to meet your needs.  While this may not be a problem as a locksmith, it makes the tool much harder to conceal if needed and also adds considerable weight making it unsuitable for use in a bug-out or SHTF scenario.

While weight and size limitations do not always make this a favorable option, it is a rather impressive destructive technique, namely for how quietly it can be carried out.  As this technique focuses primarily on gradually building up energy until the lock eventually breaks, it can be conducted almost silently until the lock actually opens.

#3 Pulling the core

While attacking the lock shackle is one of the most common methods, other vulnerabilities within the lock are much more susceptible to attack.

The keyway is one of the best examples of this, as it’s many moving parts limit the amount of reinforcement that can be placed around it. As most lock cores are meant to be quickly installed for a low cost, they are fixed into place with relatively weak material making them a prime target for attack.

One of the simplest attacks makes use of a slide hammer, which can be found in almost any hardware or automotive store and is typically used to remove dents from car bodies. These tools function by attaching to a fixed point and then sliding a weight up or down the tool to generate large amounts of force without actually striking the object it is attached to.  

Slide hammer attacks are carried out relatively easily by using an impact driver to drill a screw into the keyway before attaching the screw to the slide hammer.  While it is not always guaranteed, in many cases it is possible to generate enough force on the slide hammer to remove the core from the lock and ultimately cause an unlock.  

This attack is by certainly no means discrete requiring a loud impact driver and making considerable noise during each strike, however if done correctly can be carried out fairly quickly before anyone can locate the source allowing you time to operate.

Like other destructive techniques, carrying the necessary tools to attempt this attack is not always possible as the size of a slide hammer and impact drill makes them almost impossible to conceal.

It is important to also note with this technique that it is almost guaranteed to destroy the keyway, even if you cannot successfully force the lock to open. This is less true with the previous techniques where failure to open the lock will likely just leave some tool marks to the shackle.

#2 Freeze the lock

We’ve looked at the core of the lock and the shackle, but another weakness may be found in the body of cheaper locks and takes advantage of how metals properties change when exposed to different temperatures.

The lock is first rapidly cooled by exposing the lock to an inverted can of compressed air, which typically contains gases such as butane.  As the gas is pressurized in the can, inverting it causes it to turn into an extremely cold liquid well below freezing temperatures.

A close up of a lock

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Once sufficiently cooled, you can then strike the lock body with a hammer and in many cases cause the lock to shatter and come open.  You may need to repeatedly cool the lock and strike it however this is an extremely powerful attack against cheaper locks, which often use weaker materials in their construction.

This method can be rather time intensive, however is relatively quiet with the exception of striking the lock and can be concealed with relative ease (particularly if you are able to source smaller cans of compressed air).  

Although the standard method of this attack usually works, it may also be carried out in a slightly different way; by using a cold chisel or similar tool to focus the energy of the strike to where the lock body and shackle meet.  This increased force can encourage the lock to shatter in its weakened state, however, does mean more equipment to carry in order to carry out the attack.

Although making the attack more complex, a chisel can help dramatically with the attack if access to the lock is limited by moving the striking surface away from the lock and therefore improving access.

Ultimately, this attack may not work in against every lock however can work very well against cheaper models of locks, such as Master Lock and bargain store locks.

#1 Blow the lock up

It’s safe to say blowing up the lock is one of the most efficient ways to destroy it, but access to the necessary materials is highly restricted and next to almost impossible.  It is however possible to destroy the lock using a controlled explosion, which is much more accessible.

This explosion comes from a specialty tool known as a Powder-Actuated Nail Gun, although they may be more commonly referred to as a RAMset.  Normally, these tools use a primer to generate the force necessary to drive a nail into material such as metal or concrete.  

Although their intended use lies in construction, it is possible to use the striking surface against a lock directly, imparting an extremely large amount of force onto the lock and causing it to shatter.

While almost any surface on the lock can be attacked with this tool, it is often best to target the top of the lock.  Striking this surface in this way promotes the tool to impart extreme force onto the locking bar and in many cases will force the shackle to separate from the lock.

Powder actuated tools are relatively expensive to obtain, starting at around $50 to $100 and in certain cases require a license to purchase, however they are arguably one of the best ways to attack a lock.

The do make a large amount of noise as the energy comes from a loud explosion within the tool, but the speed at which this attack can be carried out negates the attention this attack will typically draw making it a great way to bypass locks. 

While many of the techniques included in this article are more practical in some cases, what earns this method its place at number one is its reliability.  From cheap Master Locks to higher end security locks, it is impressive just how effective this technique can be when employed correctly.

Special mentions

All the attacks covered in this article were chosen primarily because of their accessibility, efficiency and most importantly their ability to protect the object the lock is attacked to.  There are however many more destructive attacks that almost made the list, of which two earned a special mention.

Thermite is an extremely impressive means to break a lock, however, is not a practical method due to the immense amount of heat generated during the attack posing a very real fire risk to the surrounding area.  Despite the risk, thermite reactions can get extremely hot (as much as 4000F) destroying the body or shackle of almost any lock in a matter of seconds.

The second attack earning a special mention is the bolt extractor.  These self-tapping bits are typically used to remove snapped bolts, but in certain cases (such as the locks of disk brakes) can be used to force apart the locks shackle and defeat the lock.  This is extremely limited with the number of locks this can work with, leaving it out of our top five, however is very valuable against bicycle locks.

How to protect against destructive attacks

With enough force and determination, almost any lock will inevitably succumb to a destructive attack.

Although no lock is perfect, it is possible to take steps to protect against destructive attacks and there are several factors worth paying attention to when shopping for a lock.  These include:

  • A plastic cover protecting the lock body from changes in temperature
  • A recessed keyway to limit access of tools
  • A suitably sized shackle to prevent tools from being inserted into the lock
  • A lock made of a hardened steel or titanium to limit impact attacks

None of these properties will protect against 100% of all attacks however they will help slow down the attack, increasing the risk of an attacker being detected and ideally stopping them from successfully breaking the lock.

With that said, it may not be worth investing that much in a secure lock depending on what you are attempting to protect. 

Your security system is only as strong as its weakest link.  Just as destructive lock techniques are not that valuable when attacking door locks because of the presence of windows, a high-end security padlock is often not worth the investment if it is only being used to protect a weak fence or old garden shed.

It is important to always scale your lock to its individual application and truly understand where and when it is worth investing money to truly protect property.


We’ve covered a lot of techniques here today that take advantage of a range of different lock vulnerabilities and hopefully demonstrate that no lock is truly impenetrable, especially with enough knowledge, time and effort.

Most importantly with almost all of these techniques, we tried to select the most accessible ones to let you get your hands dirty and start opening locks.  With some exception, almost all of these techniques can be carried out relatively cheaply, making it an ideal skill to start practicing and add to your collection.

Cody Martin

With over 18 years of federal law enforcement, training, and physical security experience, Cody focuses his time nowadays on both consulting and training. He regularly advises individuals, groups, multinational corporations, schools, houses of worship, and NGOs on security threats while conducting customized training as needed.

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