Locksport Handbook to Challenge Locks

Locksport Handbook to Challenge Locks

This handbook was born out of a post I made on FaceBook.  It is a community document about challenge locks and information that can be used to understand and make them. To anyone who has a new concept or proven modification or pin design, or would not like anything I have pulled and used from the different social sites to be included in this paper,  please contact me and I will add or remove it.  Kurt Kiffmann on FB, u/PickSmith122 on Reddit, PickSmith on Discord, and PickSmith122@gmail.com

I want to thank everyone who contributed to this by supplying information, pictures or help editing. In no particular order; Harry Bow, Kevin Bowen, Gravity Karma, Peaceweapon, HV Logic, Isaac Hashman, Dmac, Picking Rick, Derrick Houge, J. Gabriel, Birdie, Den Brass, CajunLockPick, USMCThaxton86, Kelya Sentre now known as Climb69Trees, Georgia Jim, Picksologic, MrBlackMagic, Lethalogicax, u/Emory_B_Thomas, PandaFrog, NXT, MacGnG, Schuyler, Prince, and anyone else whom I forgot (remind me and I will add you!)

Excerpt from original post

Hello Pickaholics!

This is going to be a long read to warn you ahead of time!

Kevin Bowen/Sadistic Picker asked the question of how pins can interact with other pin designs and cylinder mods, and can you mix them up to create something different?  The simple answer is yes you can mix up pins and cylinder mods.   But is this always effective?  This becomes difficult to answer because it is a yes and no answer.

Full disclosure here, I have not made a CL, but I have picked many ranging from easy to I have not been able to pick them.  And as a locksmith I have an understanding, after seeing what the makers have done, of how the pins interact with what mods.  This will not be complete since I know there are pins and modifications I have yet to see.  I am going to do my best with what I know and have seen.

What makes a good CL?  I believe the great makers have an understanding of what works best with what.  Darren McEvoy, Harry Bow, Den Brass, and Albert Lebel make some of the toughest CLs out there.  And to the other CL makers that I do not know yet, I would love to try your CLs!  For lack of a better word, I believe they create a theme in each of the locks and make the pins and mods work together to create a whole.  They attempt to fool you by differing feedback and the feel of the pins. This is done to confuse you with what you feel.  Can you just throw every trick into a lock and the pins?  Yes, you can. Does it make a good CL?  Not always.  If you create a thought process of how you want the lock to feel and pick, you can make the pins work for you.  Every pin has a different picking technique and feedback response.  And yes, you can create pins that have multiple feels and feedback.  

What is a challenge lock?

A challenge lock is a stock lock from a manufacturer that has been modified to be a more challenging pick.  Typically pins have been modified by hand and the lock plug and housing may have modifications designed to make picking harder. 

Why do we have challenge locks?

Challenging people to pick locks has been around since locks were invented. Now we use them to be fun picks or ones to challenge experienced pickers.  In going through the LPU belt system, these are used to further educate people on how to make pins, and become even more comfortable with gutting, assembling and understanding locks. 

History of Challenge locks

Manufacturers started out by challenging people to pick their locks and even having cash rewards for successfully picking the locks.  The first example of this is the Bramah lock challenge that started in 1790, and the lock was picked finally in 1851 along with the Chubb detector lock by Alfred C. Hobbs.  Manufacturers would continue this bounty reward challenge into the mid late 1900’s.  

I have not found much documentation to support my personal choice, other than from word of mouth from other locksmiths in the Discord groups.  NXT and Peaceweapon, both commented that locksmiths would make locks difficult to pick with bitting and out of MAC specs for apprentices and to share with other locksmiths as challenging picks. 

After the locksport community was created by SSDev in the 1990’s, other groups soon followed.  Once the online forums were created at Lockpicking101.com and Picklocks.com, we can find records of the locksmiths around 2009-2011 starting to share these locks.  These were first called custom pinned locks or modded locks.  There are videos on YouTube from user Kokomolock who was picking and gutting these locks at the time. Kokomolock’s first video of a custom pinned lock was dated October 17th 2009, where he replaced all top and bottom pins with spools from LAB, then picked and gutted it.  Stock pins were the start of these locks.  Lab serrated and spools, Assa sidebar pins, gins, barrels, Scorpion lock pins, and some custom pins were starting to be used.  It appears the three main people doing this were Kokomolock, FarmerFreak, and Chriswingate from both forum sites.  Kokomo and Farmer are locksmiths.  People in passing referred to these Frankenstein locks, Frankenstein monster locks, and shortened to Frankenlock. Frankenlock was more commonly used in referring to swapping cores from one padlock to another, adding a 410 cylinder into any other Master lock, or putting a Master cylinder into an American padlock.  There is a bit of confusion here since the term was used for different things. I can see comments on custom keyed locks that they referred to them as Frankenlocks, but when I do a search I only find the posts about swapping parts of stock locks.  Frankenlock was first used around 2008

It is difficult to track down the time when the name switched to challenge locks.  At the time there was also the “ultimate challenge” practice lock from learnlockpicking.com.  I see the transition from custom pinned to challenge lock late 2013 in both the forums and YouTube. 

One user on Lockpicking101.com, Raymond, may be the first person to talk about making your own security pins in the forums.  His first post is a reply to people looking to buy security pins, and asks what about making your own pins is from June 3rd, 2007. He explains how to make security pins by using a mini lathe, drill or dremel and needle files.  Raymond also mentioned how he made anti-drill pins from drill bits. In another post in 2009 he explained the process again.  Then ToolyMcGee the following day posted a picture of a pin he made that looks very similar to a christmas tree spool driver using the techniques.  FarmerFreak in a comment mentioned how he had made Medeco pins out of screws with the true gate and false gates, by cutting the slots with a Dremel.  He was disappointed with the tolerances of these handmade pins. 

The term drunken spools was coined by Lockpicking101.com user Evan, in a post with FarmerFreak explaining how inverted Schlage T pins act when picking them in a lock on March 16th, 2011.  

In searching YouTube it is almost impossible to find the first use of the term Challenge lock, since their search engine sucks and you cannot look by chronological order.  You can only do this on a user video list. I picked BosnianBill’s YouTube channel to show his timeline of custom pinned locks to challenge locks. 

In BosnianBill’s (BB) first video of picking a custom pinned lock, custom pinned is not used by name or in the title, of a FarmerFreak lock using Schlage T pins.  BB had never seen these pins before.  This is video 153 from December 13, 2012.  In video 251, his first video showing how to modify a lock, BB explains how to modify a Kwikset cylinder with countermilling, threading both plug and housing, adding factory made security pins, and making your own pins with a drill and needle files, then send the lock to a picking buddy, this video was posted March 16th, 2013.  The first video of BB that uses the word challenge is video 259, title is “Challenge: Brinks 527 maximum security padlock”.  This is a lock sent to him and he was challenged to pick it out of the package and had factory security pins.  BB and another picker had been trading ideas of how to make locks harder to pick with mods and modified pins.  In video 304 BB picks a lock sent from Alex Blate that has modified pins and core modes.  To me this is BB’s first video with a true modern day challenge lock from another maker, possibly the first named lock since the mummified key paper had “Psychological Warfare 2”, although it was called custom pinned in the title, May 24th, 2013. BB’s first title with CL used is (442) Kerensky77’s Challenge Lock #1 (SCREWED!!! – really…), date December 4th, 2013..  FYI still no shims being used in gutting locks!  Video 451 BB makes a video dedicated to making your own security pins. 

Gallery of FarmerFreak pins and modded locks

Pins of a FarmerFreak custom pinned lock from 2009 with custom pins and a two part plug.  

I don’t see what that second shear line is for since it would never come into play in a lock. It might move a bit but the insert piece would always be held in place by the housing. 

Another set of pins from a FarmerFreak custom pinned and the threaded plug. 

The upper brass tube pins were captive in the bible and the smaller spring was what was driving the Assa barrel pins.  It seems FF was a huge fan of making locks that could not be over lifted as a bypass. 

This FarmerFreak one used a spring loaded side pin that went through the key. 

This FarmerFreak is a clutching tailpiece lock.  With trap t pins and overset traps and a special pin in six. You had to pick all the master wafers above shear and activate pin 6 to get the tailpiece to turn. 90 degrees is not an open here. 

This one has too many pictures and just has to be seen to be believed.  This is a custom dimple lock with a sidebar.  The cylinder used was a standard KIK and FarmerFreaked.  This guy is amazing in what he thinks about and is able to accomplish.  


Multiple shear lines that move side to side.  This was inspired by another locksmith recounting a tubular lock he could not pick and found out why. 

Raymond wrote:I once had to drill out a tubular lock that I just could not pick. I then took it apart and found two round, flat plates inserted between the normal shear line. Each plate was drilled exactly for all pins. Half of the pins were spools. However, there was one additional non-moving pin that would allow the plate to rotate about 5 degrees. So, if you picked the lock to the shear between the plate and the top part of the lock, you would set the plate in a position that was non moving and none of the pins would pick any more. The bottom plate was exactly the same. The key opened the lock by setting the pins at the shear line between the two plates. If trying to pick it you still would not know which plate you set your pins at and the spools would mess everything up. I wish I could remember the brand name. Happy planning.

This FarmerFreak example has a spring loaded sliding shear line and can never have a working key, but can be picked. You would have to lift pin 4 first to activate the slider to move forward, thus releasing the other five pins to be allowed to move. 

Now to the pins and what mods work with them.

Pin Types


These pins we all love and hate.  They have serrations made by creating grooves in the pins by different means. Small close together or larger further apart serrations change how the pins feel.  Sometimes they are screws that have been turned into pins.  These serrations are meant to interact with the shearline of the housing and plug.  One mod that helps reduce the feedback and cause the pins to lock up a bit more is the threading of the chambers.  This can be done in both the plug and upper chamber in the Bible.  These pins can interact with countermilling, but usually does not help confuse the picker.  Countermilling works better with other pins.

Serrations can be added to other types of pins that create problems for the pickers.  Serrated Tapers and serrated spools.  

The dreaded Rattlesnake pin!

This is a pin that is made from a t pin or nail that has wafers with holes in it that go onto the post of the pin. Then the pin is peened at the top locking the wafers onto the pin.  These are now free floating serrated pins that wreak havoc and confusion with any level of picker.  When used in conjunction with threading of the chamber, all I can say is good luck!

Recently Harry Bow and J. Gabriel have created the pin in pin rattlesnake.  Talk about horror!

Picture from Dmac


Spools come in many shapes and diameter of the material removal causes differing false sets.  Some of the different types are standard, hourglass, extreme (my word for extra thinning of the interior of the spool portion), barrel, serrated, stepped, drunken, and gin (more on this in the next section).  These pins are made to interact with the plug and housing shear line, causing extra rotation of the plug, called a false set.  These pins are picked when the feedback of counter rotation is felt.  Countermilling increases the false set rotation and can create almost a bound pin feel with less counter rotation feedback.  In the event of extreme countermilling this can also cause a dead core where no feedback is experienced.  Float picking is needed in this situation.  Using a serrated spool with and without threading the chamber can cause differing feedback and feels.  Serrated spools will also work well with a threaded and countermilled chamber.  Thin lipped spools will also work well with threaded and countermilled chambers.


Gin pins are a version of a spool that deserve their own section.  Gins are a reduced diameter head spool pin.  These are used in conjunction with squared countermilling to create a locked up feel of the plug and pin.  Assa gins are the pinnacle of this pin and that is why the 600 and 700 cores rate higher than even some side bar locks.  The difficulty of learning float picking and the ability to set these pins might be one of the hardest feelings to master.  In CLs the ability to create that squared countermilling is extremely difficult to recreate with hand tools.


Tapered pins are where material is removed at an angle on the end of a pin, creating a taper to the center or end of the pin.  This type of pin gives very little feedback as it is being picked.  Subtle core movement can be very difficult to feel.  A bottom pin that has been tapered can also cause a rotation back to the resting position of the plug.  Using a top and bottom taper can cause havoc with the feel of picking these pins.  Nudges are used on these pins to see where you are in the picking of it.  If you can even feel the difference in the movement of the pin and plug.  These are some of the hardest pins to pick in my opinion.  Tapered pins work best with unmodified chambers.  But Dmac and others have challenged this notion by creating serrated tapered pins and adding threading in the chambers to confuse you even more.  Harry has used these to really confuse the picker, he has used a reduced diameter taper top pin that wobbles and locks up in the chamber adding to the confusion.  He has used  top and bottom tapered pins in the same chamber.  One item of note if you are going to try this configuration you must make sure that the two taper ends have a large enough of an end diameter to not fall into each other causing a serious issue of locking up the core.

Reduced diameter

These pins are smaller in diameter than the standard pins.  These will wobble in the chambers and create small core movements.  I have only seen a few of these in CLs and I have a feeling they can cause more problems than the confusion they sow.  Hopefully the makers who have tried these can expand on this section for us.

I have now seen more of these in locks and I am still on the fence if this changes feedback or makes a lock harder to pick.  The pins do seem to move differently when you’re picking. I believe the pins are from the cabinet or padlocks that I have seen.  These were not handmade but factory pins. 

Pin in pin

This is exactly what it sounds like.  Usually an outer sleeve with an inner pin.  These are usually accompanied with a matching top pin in pin with two springs to make each part work independently of each other.  Harry has used these to great success and personally the feeling of these is weird.  He has made the outer sleeves of standoff pins with the inner portion being threaded and has added serrations to the inner pin to create a serrated pin in pin.  Crazy weird feedback on these pins!  In one CL, Draugar, he made pin in pin gin pins with countermilling.  This was a lock I was unable to pick, and the feedback confused the hell out of me as to what I was feeling.   I wonder if anyone has made a serrated outer sleeve with threading the chamber?  That would be horrible to pick!

Harry and J Gabriel have both made a pin in pin in pin now, and another user on Discord had created a four piece pin in pin (sorry will add his name later). 

Two-part pin

These are pins that are made of two parts that usually interlock with a pin tip and a hole to receive it into.  These pins are made to allow you to overset the pin and dampen the feedback from that pin.  If you do not overset it, it feels like a standard pin.  I have seen serrated versions of this with threading on the chambers to make it tougher.

Harry Bow just showed me a top pin version of this but he called it a Pin in Pin. But it was a top pin with two parts and a spring between the two pins and a main spring would go above this composite pin. 

Many call these pin in pins but they are not a true pin in pin.  

J Gabriel makes a catastrophe pin that has multiple parts. Catastrophe pins are a three part pin that are not fixed to each other.  These were named due to the possible catastrophe of gutting by the unwary. A brad that has a brass ball and a third part that can be serrated or spooled are common to be found.  The picture below of Nothing Fancy has Catastrophe pins in chambers one and six.  Along with rattlesnake pins with fine wafers. 

Another example of J Gabriel’s Catastrophe pin and a rattlesnake key pin in chamber 5

Den Brass Kick Ass 2 piece pin in pins pictured below

Prince’s Analog using both 2 part pins and a PIP

Other examples of 2 piece pinsLower picture from u/Emory_B_Thomas

Magnetic pins

This is a Harry special that I have not seen done by anyone else yet.  He uses Neodymium magnets to create pins that attract to each other.  I have picked a couple of locks now with these and the feedback I likened to an oxymoron.  The feedback is confusing since once you set these pins the bottom remains lifted, almost causing you to think you have overset the pin.  You will not get the loose pin feel of a set pin with these.  He adds serration to these to only make it harder.  If you’re using steel tweezers these will magnetize them!  Use nonferrous springs with magnets!

Harry Bow’s #89 Grendel with magnetic pin with serrations

Update, I have now seen a pin in pin where the inner part is the magnet and the driver is one as well, with a drunken spool over it, Harry is a madman!   Basically a large T pin and a magnetic wafer on the end. 

Harry Bow’s #87 Imp chamber 3 with magnetic PIP and magnetic drunken spool driver

T pin

Typically, this is a half spool.  Schlage uses these in their cheap locks to have a reduced height spool effect.  If inverted this creates a reduced tip pin, and are called drunken spools.  It causes a false set and requires nudging to lift above the shear line.  Harry took these a step further in a lock.  He used the standoff screws that had the male threaded end on them and threaded the core to create a serrated reduced diameter top pin.  Talk about evil!

Another pin I didn’t know about contributed by Isaac Hashman

The lopsided pin

First of all, you can make any pin lopsided, so it applies to all the different shapes. Secondly, the feedback is similar to the shape you are replicating but it will feel distinctly different each time you pick it. Some pins will rotate, such as a lopsided T pin. You will get the false set, but then feel the false set go a bit deeper as the pin rotates slightly. So in many ways it will replicate the feedback of the pin you are basing it off of, but also adds a level of randomness and variety to how that pin will feel each time it’s picked, depending on the state and orientation the pin is in at that time.

Others have started calling these asymmetric pins. 

Springy Pins created by Peaceweapon

A specific type of 2 part driver pins in which the inside pin, usually a T-pin, is spring loaded from inside the outside driver pin. The outside driver will feature different security modifications – spooling and serrations – and, as the combined pin is pushed up until the outer driver binds in one of those security modifications, the inside spring will give springy feedback to the picker. This effect can be combined with plug modifications to make it harder to set the outer driver pin, and afterwards, to set the inner T-pin.

Reverse t-pin overset traps

Specific type of two part pin in which the inside reverse t-pin can be trapped above shear line while the outside key pin will be loose and even give springy feedback.

The inside key pin can sit on the bottom of the outside key pin or go through it. One variation includes a reduced diameter section on top of the t-pin and adding overmilling, making it easier to overset and harder to drop the overset.

Single ball bearing and reverse t-pin keypins

A 2 part key pin where both parts don’t interlock in any way, and the bottom one is a ball bearing. Makes it hard to interpret feedback and place the pick. The reverse t-pin on top will increase overset potential.

Others have used ball bearings and master pins to create the bottom pin.  Picks tend to roll off of the bearings and have a weird feel while picking.  Peaceweapon just made it evil!

Ball chain drivers and key pins  Using a chain of small balls as drivers or keypins. They will cause a deep false set and have weird feedback.

Themed Pins

HV Logic has created themed pins.  One set are bowling pins and a ball from “Strike” and the second are food items found at your county fair and called “County Fare”. From left to right: Caramel apple, ice cream cone, ear of corn, hotdog, spiral potato, and popcorn bucket.  

HV Logic’s HIGH VOLTAGE with driver pins shaped as electric insulators

Munition pins from Downundermonkey’s Frag Out

Key pin mods

Key pins can also be modified.  Adding serrations, tapering, spool tops or mushrooming adds the effect of modifications to the plug or housing.  Spooling is commonly called an overset trap, and the pin is commonly called a torpedo after the Assa/Ruko torpedo pins. When lifted above the shear the lock will remain in the false set, and depending on shape, continuing to lift the pin creates more feedback.  But not the kind of feedback a picker wants to feel. 

Gallery of pins 

J. Gabriel

Pins by u/CuriousLockPicker

Pins by u/Nitiflor Pins by u/UKLockpicka

American padlock CL and pins by u/pol-delta

Cylinder modifications

Threading is done by using a threading tap in both the upper bible chamber or the plug chamber.  Sizes I believe are 6/32” or in metric m3.5 tap. It is recommended to lightly file the chamber threading, failing to do so can cause pins to lock up. 

Counter milling, also referred to as undercutting,  is the undercutting of the plug or bible chamber just below the shear line.  This is done with small bur bits. This can be done with round, Hart, saw tips, or knife edge burs. Different shapes will have different effects on how the pin catches and the technique required to get the pin free from the milling. A round milling will allow the pins to be pushed out by the bottom pin, where any sharp or square milling used with sharp edged spools or gins may need to be float picked out of the milling.  Countermilling only needs to be done to the left and the right of the pin chamber, but some makers find it easier to run the bit in a circle within the chamber.  

Overmilling is the enlarging of the pin chamber right at the shearline.  This can be done with a milling burr which is a cylinder in shape.

Some examples of over milling below

”Ya, bend the rules” by Gravity Karma   Newton by Gravity Karma

In the picture on the left the overmilling steps are enlarged as much as they can be without dropping pins in normal operation. The steps are matched with serrated GeGe type pins so as to lock hard. The Picture of Newton on the right shows a milled core and deep undercut matched with a spool to give a large false set that still requires rotation back to set it.

Shifting Perspective by Gravity Karma On the nature of Patience by Gravity Karma

Shifting Perspective has a deep cut matched with a long and thin spool for a nearly 90 degree false set. On the nature of patience has more pin and milling matching shenanigans. The overmilling depth matches the spool top depth so as to give a false set with a hard-locked pin. Chamber 4 is milled deeper and wider so an unset pin jiggles as if set.

Posted by HV Logic

Split core this is where the plug is cut in half or more pieces.  This is done across the length of the plug.  Splitting the plug with the length is asking for disaster.  Gravity Karma is toying with this and we will see what he can do with the concept. 

War on Peace by Gravity Karma – the plug is retained by grub screws that ride in the channels you see below. The central section is relieved to make tensioning difficult

Image found on google with split core

Other mods

Sleeper by Gravity Karma – In this lock there is a partial sleeve giving additional shear lines. Partnered with a master wafer this can easily cause an unrecoverable false set.

Gravity trapbar by Peaceweapon

Addition of a bar fitting on the bottom of the keyway that will be trapped inside a groove in the lock body. This will be especially effective against American pickers, who pick bible up, as it will force them to pick bible down. It will also reduce the size of the keyway, blocking the bottom part of it. Pushing the trapbar to add space while picking will effectively trap the plug.

Trap with a Tpin 

This has been done in a couple of other locks.  Choices by Dmac and I have heard of another but cant remember who it was.  

If you do this mod you must make sure that the plug will counterrotate back to center.  This is done by beveling the reverse edge by the chamber hole.  Otherwise it’s a bricking trap. 

Gravity trap

This differs from Peaceweapons gravity bar but is the same principle.  I just found this in the American three monkeys CL set.  I cannot tell you how it has been done, but it does work.  #2 made by Nosepicker/Leyton Short, has this feature in it.  You pick the lock like you normally would either direction and the plug will turn about 45 degrees then stop, but also something that restricts the plug from turning back completely.  To get the open on this lock you must turn it upside down and while slowly rotating the plug back and forth rotate the lock on the plug axis slowly, at about the 60-90 degrees the plug will then allow you to turn it to the open position.  When attempting to return the plug back to the locked position sometimes it will not return and the rotating of the cylinder is required for a reset.  The key works perfectly in the pins up orientation, but if you rotate to pins down the key will lock up in that 45 degree location.   

Another version of this is one I came across in a couple of challenge locks now.  The maker puts an overlarge bottom pin in a chamber with no driver or top pin.  This makes the lock unpickable in the pins up orientation and must be turned over to pick in the euro style pins down. 

A second version of this included at spring to hold the pin down, you had to push the pin above the shear line into the upper chamber to pick the lock. 

Ball bearing blockers

Harry Bow in his BallRoom challenge lock, installed ball bearings from the side with springs to press them into the far wall of the keyway.  When first installed this limited the ability to push or pull the pick through the keyway.  You would have to insert the pick around these balls to get to the pins.  They were installed offset from the pin chambers so you did have access to the pins. 

Sleeved plug

This has been done in manufactured locks as well.  Harry Bow has done this on a couple of locks now.  He reduces the diameter of the plug and installs a thin brass tube over the plug.  The tube has had the pin chamber holes drilled into it, along with a slot in the side where he puts a pin in a hole in the plug but is flush with the sleeve.  So the sleeve can rotate around the plug, this makes it impossible to lift spools out of the plug chambers.  In this type of lock a deep false set is a no go.  Reset and try again. 

Other trick modifications

Milling out the outer upper part of the keyway to remove the ability to pick using TOK. 

Challenge lock from MrBlackMagic using extreme mods

“Assa 700 lockbody with some nasty modifications.

Keyway blocker, undercuts and anti-tension mechanisms such as a new type of security driver are just some of his features.

It’s a beast designed to be unpickable and to break every lockpickers self esteem as well as their picks.

It is his desire to see this moment when all hope leaves the body and hate is building up.

Try at your own risk!”

Mods that I call cheap tricks

These mods are done in a way to restrict key ways or do something that makes it near impossible to pick a lock.  

Gluing pins in place

Blocking keyways by gluing half a key in the keyway, but this mod has been used many times and the locks are still pickable. 

Extra spring pressure that could turn a CL into a pick breaker

Trap pins that brick a CL

Building your challenge lock

Testing your pins with each other one at a time in the lock you are using is suggested. Use the key in the plug when putting the plug back in so you can feel if the stacks are too large and the key is rough in coming out.  Using a large driver and key pin will not allow the key to smoothly insert or pull out of the lock.  This will cause spring compression and chamber failure in the long run.  Larger bottom pins need smaller top pins and vice versa.  It is a good idea to take a look at how your pins will work with the shear line by putting the pins together in the plug out of the housing.  This will allow you to really see how those pins are going to interact with cylinder mods and the shearline. 

Using grub screws in KIK, mortise and rim cylinders should be avoided.  This reduces the chamber height and will require smaller pin stacks or shortened springs.

Selecting keys or making keys with challenging bitting is recommended.  Flat bitted keys and keys that have many deep cuts should be avoided, since deep cuts tend to be zero lifts. A challenge lock where you have to only pick 2-3 pins is not much of a challenge. Pin and cylinder mods work best with pins that have movement in their travel.

Engraving, artwork, carving the cylinder, and naming your locks is encouraged and creates a unique look to a unique custom made lock. Picksologic made this comment on Challenge-Locks.com “I have noticed that most CL makers put all their creativity inside the lock, but do not do much to the outside. I would like to inspire them to work on the outside too.”

“Cash” from BanditoBrandino07 “Engine” by Picksologic

Streamliner by Picksologic Aztec by Picksologic

Dmac’s Jolly Todger

The 2021 Locky Award winner challenge lock “Frag Out” by DownUnderMonkey

Dazzling b.s. From Hillbilly Locksport

World’s smallest challenge lock by PandaFrog “Petit Laiton” made of a 15mm Kasp padlock.  Petit Laiton translates to Small Brass in english. Photo by GilliGainz

Things to watch out for in selecting locks to use

You should not use cylinders that have the construction keying holes, or if there are any cutouts on the plugs.  A T pin or a PIP can lock into these and not come out.  Bricking a CL is not what we want to happen.  

Extra long Euro cylinders should only have driver pins that do not require the use of a shim.  Most of us pickers are not going to have extra long shims to be used for these cylinders.  Extreme tapers, gins, inverted T pins, and PIPs should not be used in these.  Grubbing these long cylinders will help the pickers gut these if you do choose to use pins that require a shim for gutting.

Requirements of making challenge locks for Lock Pickers United belt ranking system

Challenge Lock Requirements

Blue Belt Picker and higher require that you have custom pinned a “Challenge Lock” and shared it with another picker. Preferably this lock will make it into circulation and introduce you to the fun of exchanging locks designed not for security but specifically to defeat picking. If for some reason you are unable to fully engage with the larger community of exchange we still encourage you to gain the more in-depth knowledge of how locks function that comes from building your own. Speak to a moderator about possible alternatives to the challenge lock requirement. Having no interest in building a challenge lock is not grounds for an exception.

A “Challenge Lock” is defined as:

A commercially made lock and working key that includes a minimum of SIX modifications by the lock builder. Number of modifications must total or exceed SIX and may include any or all of the following:

  • Turned, sculpted or shaped key pins
  • Turned, sculpted or shaped driver pins
  • Modification to the chambers by threading or counter-milling
  • Improvised secondary locking mechanism
  • Distinguishing mark engraved into the lock
  • Hand cut key


  • Each “turned, sculpted or shaped” key pin counts as one modification. Pins must be shaped BY the builder, removing no less than 15% of the original material
  • Each “turned, sculpted or shaped” driver pin counts as one modification. Pins must be shaped BY the builder, removing no less than 15% of the original material
  • Pin-in-pin counts as one “turned, sculpted or shaped” pin per pin modified. Shaping a pin and also making it pin-in-pin does not count as two modifications
  • Chamber threading counts as one “modification” regardless of the number of chambers augmented
  • Chamber counter-milling counts as one “modification” regardless of the number of chambers augmented
  • Each improvised secondary locking mechanism counts as one modification (latches, check pins, etc)
  • “Distinguishing mark” engraved into the lock counts as one modification (Simple scratches do not count. Engraving must be a symbol or mark of the maker)
  • Hand cut key counts as one “modification”. The key must be cut using hand tools from a blank, and must be a reasonable bitting. Locks made with 0-bitted, or minimally bitted keys do not count.

Copied from Challenge-Lock.com

Challenge lock guidelines

Created by Keyla Sentry (Climb69Trees) in cooperation with the Lockpicking community.

For Makers: 

  • To meet blue belt requirements, a CL must contain at least 6 approved modifications. Beyond the blue belt requirement, there are really no hard rules. Following this guide will make a better experience for everyone. 
  • Always be courteous and gracious. Treat each other well. 
  • Please be safe. Power tools and heat sources can cause serious injuries. Please familiarize yourself with workshop and power tool safety. Wear appropriate safety gear, especially safety glasses or goggles. Gloves are often not recommended around rotating machines. Consult the owner’s manuals that you should have already read. 
  • Must be pickable. If it’s an extreme challenge, likely to break picks, or otherwise extreme in some manner, make it well known. No one wants to break all their picks in the pursuit of fun. You also don’t want a high-black level lock to go to the average orange belt picker. 
  • Must include a working key, unless it’s to be impressioned. Include a key tag with whatever name you prefer and the name of the lock. Maybe even include the date finished. 
  • Include any unusual tools that may be required. We have shims, screwdrivers, and hex keys, but anything custom made for the lock should be included. State size needed so we don’t have to search. 
  • If your lock has trap pins and you can’t back out, you need to include instructions. It’s preferable to use grub screws so you can gut only the offending chamber. It should also be disclosed when sharing such a lock that it contains them. (There is some disagreement on this one.) 
  • Sometimes you need to include detailed instructions. “Please Gut” if you’re proud of your pins. Something like “Do Not Gut!” if it’s a nightmare inside. 
  • If this is your blue belt challenge lock, you may post pics to the moderators to prove your mods. Then your picker only has to confirm shipment tracking. This will greatly speed up your belt upgrade.


  • These aren’t required, but they’re recommended to provide the best experience for both maker and picker. 
  • Name your lock. People will remember it, and it will be easier to talk about and track. 
  • Pick the lock you made. Is it a challenge, or is it a basic lock with fancy pins? 
  • Make an effort to understand how your mods work and interact. This is the whole point of the challenge lock requirement for blue belt and up. Just throwing a bunch of random mods into one lock doesn’t magically make it challenging. Often it’s quite the contrary. 
  • Test the mods extensively. Do all the things to it that others will do. Do them multiple times, and don’t be gentle. 
  • Letting the person know general “belt level difficulty” is nice, as well as telling them if it needs to be shimmed. On that note, it’s best to shim all locks, especially challenge locks. 
  • Tell us if it can’t be picked with commercial tools due to MACS violations or whatever other reason. 
  • Likewise, it’s nice to know if the lock requires dimple picks or other tools besides standard hooks. Not everyone has the required tools. 
  • It’s probably best if the key is obscured, i.e. separately packaged so you can do a blind pick without knowing the key until you decide to. 
  • Opinions vary, but this is worth your consideration. Avoid cheap tricks, especially if they make a lock impossible to pick. For example, a trap pin that bricks the lock, thus requiring gutting, does nothing for anyone. Some keyway mods are cheap tricks, such as grinding away the face to make tensioning difficult. With that being said, “prank” locks can be fun sometimes. 
  • Consider registering your lock at www.challenge-lock.com 
  • Take pics and videos, share them, and have fun!

For Pickers:

  • You may know that there is a challenge lock requirement to earn a blue belt. If you accept a requirement lock, be willing to get to it immediately. At least be willing to gut it for verification before you pick it. If the maker has sent proof pics to the mods, you will only have to confirm shipment tracking or receipt of the lock. 
  • Add a key tag to any unmarked keys you get. Put as much relevant info as you have. 
  • If you get a “box set”, Do Not Separate! They’re to be experienced together. This is different from receiving several challenge locks at once. A box set will be obvious. 
  • A challenge lock, once sent out, is considered community property unless specifically gifted to an individual or otherwise noted by the maker. 
  • When gutting, make sure you check the pin chambers for mods. They can be surprisingly easy to miss. 
  • If you break any part of the lock trying to pick it or gut it, TELL THE MAKER! Things happen, and we assume no one would intentionally break a challenge lock. Work with them to repair it if possible, or send it to the maker for repairs. Or, work out a modification that makes it a CL again. 
  • Try to tell the maker where their lock is, and where it’s going next. You won’t be able to find some, and others won’t care. That’s just how it goes. 
  • Don’t intentionally damage or destroy a CL unless it’s yours. 
  • Don’t modify a CL unless it’s okayed by the creator. 
  • Challenge Locks are intended for SPP only unless otherwise specified by the creator. Never attempt to rake or impression a CL unless it was built specifically for that purpose. 
  • CLs are for trading, not for collecting. Life happens and we all sit on a lock for too long sometimes, but please try to move them along eventually. 
  • If you receive a CL that secures some sort of prize, replace it with similar prize before passing along. 
  • Check www.challenge-lock.com and leave a message. This could satisfy the recommendation to tell a maker where their lock is currently located. 
  • Take pics and videos, share them, and have fun!

List of commonly used tools

Safety Glasses! 

Dremel, drill or drill press, mini lathes are used to spin the pins to shape or drill them. It is recommended to use something to lock down a dremel if you use this, so you can use both hands on the tools you are using to shape the pins. Safety First!

Saws and items used for creating serrations: Jewelers, Fret, Coping, Razor, Hack and even knife blades

Files: Needle files are best and there are some great shapes that come in a set.  Buying a better brand pays off in the long run.  Stay away from the diamond ones since they tend to leave the pin rough and are usually larger in the shapes. 

One type of needle file that I do not hear about is the riffler file.  These have curved ends and different profiles.  I do not know if these would work as well on pins as they do on wood. 

Sandpaper for smoothing out the pins after shaping. 600-3000 grit are the ones mentioned by makers. 

Micro drill bits

Pin Vise for holding micro drill bits

Vise for holding plugs and housings while modifying. 


Plug holder Birdie on Discord has created a 3D printed plug holder for use with milling techniques.  It is able to compress to hold the plug flat and steady for you.  He may have put it on Thingverse. 

Pin materials

Lock pins can be modified or you can make your own using brass rod, capillary tubes, or almost anything that is the correct diameter to fit into a pin chamber. Standard pins in the US use a pin diameter of .115”, which is 2.9mm.  A 3mm brass rod is what many use to make their pins.  But you will have to reduce the diameter a little bit to fit into the pin chambers. 

Here is a quick diameter list of common pin sizes for the US and a couple I found for special European brands

Standard lock pins .115”

SFIC .108”

Cabinet pin tumbler locks .095”

Master, American, and padlock clones .093”

Abus padlocks seem to vary depending upon source .093-.095”

Assa600/Ruko/TrioVing 2.9mm

Evva, Kaba, Gege cylinders 3.1mm

Climb69Trees – “I mention this spiral-cut rod on occasion. I got it out of a cd-rom drive. The laser rides on it. There should be one in any drive that reads via laser.”


Commercially made springs are usually phosphor bronze or stainless steel (usually a poor quality since magnets will attract the SS springs).  Steel springs should not be used with magnetic pins.  Another spring that CL makers use are lighter springs or the anti bump lock springs that have the nickname of super springs. 

Doubling and even tripling the springs in a chamber increases the strength of force against the pins.  

I suggest that the makers that use extra spring pressure make it known about that CL.  Making a pick breaker of a CL is just mean and should be thought of before making one. 

In my original post on FaceBook, I asked makers for their thoughts on building these locks.  And these are the responses I received.  I hope to expand this section from anyone who would please send me your thoughts or philosophies on making challenge locks.  

Richard Smee Matthews – Picking Rick

I may have only really made/customized 2 locks myself, but I spent a lot of time observing and discussion this very subject; so my own 10 pence, if I may 😊

The trick with these pins isn’t exactly what “type” of pins you use. For me, it comes down to knowing what will interact best with regards to bitting, taking the lock’s binding order into account to cause inadvertent pin resets, and (most importantly) what modifications to the core/body will pair best with the pin choices.

A threaded chamber will do next to dick for a deep spool; but if you countermill the chamber instead, that will create a world of hurt. Or use a wafer with a T pin to create a drunken spool to add to the feedback messing with your senses. Even better, use an Assa barrel with a threaded chamber and a reduced diameter key pin, and watch the crying begin 😁

So that’s just my opinion in a nutshell. I know I reiterated points you made, but the main thing for me is knowing what to pair with the pins and considering binding order; this, imho, is what separates a CL maker from someone who just pisses around with a dremel and a m3.5/m4 tap 🙂

Darren McEvoy – Dmac

Lots of great info Kurt. Most of the challenge locks I’ve built have had a fair bit of thought gone into the build. For me it usually starts with the key bitting. That inspires what I’ll do to each pin and the pin chambers. Each decision leads to or influences the next. I’ll always test pick them and regularly adjust them if one of my mods isnt working as expected. It’s worth bearing in mind that over-modding can reduce tolerances to the point that the lock will be easier to pick. I like to mod all the pins if I can as I just can’t resist it! 😆 I hate to leave standard pins in there. Usually it’ll just be a single shallow serration but I’ll know its there and I can then sleep easy

Derrick Hogue

Excellent read! CL making is a personal craft. The creator is the one doing the crafting to what they like, enjoy and what they feel is challenging to them. Now granted, the manufactured base lock dictates this. A good CL maker realizes the potential and capitalizes on the manufacturing process to keep it fun, and even more so challenging. I like to put a variety of different types of pins into a lock and sort of see how the lock will operate when being picked. It is hit or miss. Some roll over easily with what I thought would make it tougher. Some I can’t open easily or at all, even breaking picks.

Another thought is the pin is only good if other factors come into play, the types of chamber modifications, plug modifications,keyway warding, keyway opening size/shape, springs types, additional security features-sidebar, trap pins, check pins, etc.  So in short see what you have base wise and what you can do with the tools, raw material and knowledge. Next you have to check to see if the lock can handle and operate smoothly/correctly and it will last relatively long given the repeated picking abuse.

I found this in doing research about challenge locks, this is a post from Georgia Jim from Reddit

Georgia Jim

As to what is a good challenge lock that’s subjective, personally I like to pick CL’s that have lots of movement and keep you engaged. The ones that are more subtle are a lot harder to pick as it keeps you guessing.

Here’s some things I’ve learned from building challenge locks that I think are worth keeping in mind depending on how you want certain pins to act.

Less is more: With pins the less you do to them the harder they are to pick. Deep ridges and serrations create lots of fun movement but all that feedback talks to the picker which makes it easier for them. Small subtle mods to the pins are much harder to figure out. Also going too thin on your pins will cause them to snap from use. A challenge lock will be passed around the community for a long time and the super thin pins don’t hold up to the test of time.

Playing with the thickness of your pins makes them easier to drop especially when paired with thicker pins with spool or mushroom shapes. Once you’ve shaped a pin just put sandpaper to the pin while spinning at a low speed to remove a little extra off to make it slightly thinner than the other pins.

Threading makes pins harder to lift but also harder to drop the pin, matching the driver with a key pin that’s easy to over set works well.

Lethalogicax (I found this on the same post as the Georgia Jim above and found it pertinent to this)

Here’s where I give away my trade secrets. I have a pretty formulaic approach to making challenge locks. You definitely don’t need to follow this, it’s just what I do. I break my lock into 3 components. First, I like having at least one standard or serrated element, usually 2, so the picker has to fight for a while to drop it into a false set. Second is spooled elements. There of course needs to be spools to pick out of the false set. I try to get 2 or 3 spools per lock and never the same shape so each spool gives different feedback. Lastly, I like to put in a trap of some sort. Basically some kind of pin that makes it incredibly hard to tell whether it’s set or not. Usually I throw a t-pin in somewhere near the back but Ive also warmed up to cutting deep spool elements into the keypins as overset traps.