The Pencil Test

Imagine you're looking at a used pistol with an intent to purchase it. If it has been well used, chances are that some parts may be worn out or broken. One part, in particular, is the firing pin, which may be broken, bent, blunted etc. Another part of interest is the mainspring, which may have lost some of its strength. Or perhaps you stripped your pistol in order to clean it, and you aren't sure if you put it back together properly. There is a simple test to verify that the firing pin and mainspring are working satisfactorily and this test is the pencil test, which we will study about today. The only tool you'll need to conduct this test is a pencil with an eraser tip on one end:

A standard #2 size pencil. Click on the image to enlarge. Public domain image.

1. First, make sure the pistol is empty.
2. Cock the pistol, making sure that it is still empty.
3. Insert a pencil with the eraser end first into the barrel and push it as far as it will go (do not force it, just push it in gently). For best results, use a new wooden pencil (such as a standard #2 size pencil, like the one pictured above), with the eraser in good condition
4. Hold the pistol vertically, with the barrel end aimed upwards.
5. Make sure that the pistol is indeed empty, then pull the trigger.
6. If the firing pin and mainspring are working correctly, the pencil will move noticeably. In many pistols models, the pencil will actually come shooting out of the barrel. If the pencil doesn't move, or only moves weakly, there may be a problem with the firing pin or mainspring.

This test works on various pistol models, both hammer-fired and striker-fired types. Of course, the distance that it comes shooting out of the barrel depends on the model of pistol and also the wear and tear of the parts. For 1911 pistols in good condition, the pencil should come flying out and go at least a few feet up in the air. Glock pistols will also propel the pencil out a good amount of distance, but generally not as far as a 1911. Of course, the test also depends on the shape of the firing pin and the hardness of the eraser. For instance, in some models of M&P pistols, the firing pin may pierce the eraser instead of shooting it up. In such cases, if the pencil is put in with the unsharpened end in first, it may come flying out better. Alternatively, a plastic ballpoint pen, such as a Bic, may be used. In general, hammer fired pistols tend to propel the pencil out farther than striker fired models.

For pistols that are equipped with decocking levers (such as Sig Sauer, Ruger P95, Beretta M9 etc.), a similar test may be used to ensure that the decocking safety mechanism is working properly. As before, the pistol is cocked and the pencil is pushed in as before and the pistol is held vertically. Then, instead of pulling the trigger, the decocking lever is pushed instead. If the decocker is working correctly, the pencil should not move at all. If it moves, that means the decocker is not working properly and the firing pin is contacting the eraser.

Now on to some videos, so that you can see what it looks like.

The first video is from user Sadie Thorne on youtube and shows a quick test with a 1911 type pistol.

This video comes with no explanation, but shows the test very nicely. Notice how far the pencil comes flying out of the barrel, when the trigger is pulled.

The next video is by stdlfr11 and shows the same test done using a CZ-75 pistol.

This video has the user giving an explanation of the test, as it is being done. Note that while the pencil moves noticeably, it doesn't move as far as the one in the previous video. The reason for this becomes clear when the user pulls the pencil out as you can clearly see the indentation that the firing pin made on the eraser, which could explain why it didn't fly out as much. If the eraser had been harder or if the user had put the pencil in with the unsharpened end first, it would probably have flown out of the barrel much better. The test does show that the firing pin is functional and is not broken.

So there you have it, a simple test using a pencil ensures that the firing pin and mainspring are working satisfactorily.

Trigger Mechanisms of the AR-15 and the M16

A little while back, we studied how the trigger mechanisms of the AR-15 and M16 rifles work, complete with a video with animation explaining the concepts.

In today's post, we will look at a couple of videos that show the actual parts, instead of a 3-D Solidworks animation.

First up, an explanation of the AR-15 trigger mechanism:

Next, we have another video, that discusses the trigger mechanism of a M16 and compares it to that of an AR-15

Note that the M16 trigger mechanism being discussed is the M16-A1 model, which is capable of firing in semi-auto (single shot) and full-auto modes (unlike the M16-A2 and A4 models, which can fire in semi-auto and 3-round burst modes only). The AR-15 is capable of semi-auto fire only.

Happy viewing.

How do Firing Mechanisms Work - IV

In our last post, we saw a video that showed the basics of a bolt-action firearm, A bolt action is in the class of manually operated firearm actions. In today's post, we will study a few different classes of firearm actions, which we have already studied the basics of many months ago.

1. Manual bolt action.
2. Gas operated action.
3. Blowback action.
4. Recoil action.

In the above links, we studied these actions using some illustrations and also studied some specific variations of these actions (e.g.) short recoil action, long recoil action, direct gas impingment, short stroke gas operation etc. We also studied examples of weapons that used these different actions.

Thanks to the efforts of the US Army, we actually have a movie that illustrates the basics of all of these actions.

The video clearly illustrates how the various actions work, far better than static images do. Happy viewing!

How do Firing Mechanisms Work - III

In our last couple of posts, we saw a couple of examples of semi-automatic, full automatic and three round burst mechanisms. The first video was prepared by the US Army to train soldiers. As it turns out, the Army had actually prepared a set of videos. The first in the series showed an example of a bolt-action firearm in action. We will study that video in today's post:

Interestingly, the video shows a hammer fired and a striker fired mechanism and also deals with extraction and ejection mechanisms, as well as loading new ammunition from a box magazine.

Happy viewing.

How do Firing Mechanisms Work - II

In our last post, we saw a movie showing how a firearm could implement a mechanism to shoot in semi-automatic and full automatic modes. Of course, the video showed one particular way to achieve this, but there are other ways as well.

In today's post, we will study another mode of firing: burst mode. Burst mode is an intermediate between semi-automatic and full automatic firing modes. In semi-automatic mode, the weapon will fire one round per trigger pull and the user has to release and pull the trigger again to fire the next shot. In full automatic mode, the weapon will continue to fire automatically as long as the trigger is held down and there is ammunition available in the magazine. While full automatic firing provides a lot more firepower than firing in semi-automatic mode, it also tends to waste a lot more ammunition, especially if soldiers are inexperienced and hold down on the trigger for longer than necessary. The recoil from firing in full automatic mode also leads to inaccuracies. Burst mode provides a compromise between these two firing modes. When a firearm selector is set to fire in burst mode, it will fire up to a set number of rounds (usually 2 or 3 rounds) per trigger pull. After that, the user has to release and pull the trigger again to fire the next set of rounds and so on.

In Vietnam, the US military found that new soldiers often ran out of ammunition in combat, because they had set their M16 rifles in full automatic mode and shot their entire supply of ammunition in a few seconds (and often without hitting their targets). Therefore, they requested that the M16A2 model remove the full automatic mode option and implement a burst mode instead. Their studies showed that a three-round burst provides the best balance between firepower, accuracy and conservation of ammunition. This is why the M16A2 and M16A4 models and the M4 carbine models have a three-round burst mode.

A person named "Stealth the Unknown" has prepared a great video showing how these different firing modes were implemented on the M16 family of rifles:

In the case of M16 models, the burst mode is implemented by a rotating cam. The same video also describes how the mechanism works for semi-automatic and full automatic modes.

The same author also prepared a second video answering some follow-up questions about this mechanism.

For instance, in a M16, if the user releases the trigger before a three round burst is complete, then the next trigger pull will only fire 1 or 2 rounds. This is because the M16's cam mechanism does not reset when the trigger is released. In some other firearms, the mechanism resets every time the trigger is released and therefore the next trigger pull will fire the full number of rounds. The author of the video also goes into an interesting theoretical design where he designed a selector with multiple burst firing modes as well as a semi-automatic and full automatic modes.

Happy viewing.

How do Firing Mechanisms Work - I

Hello everyone, I'm back from my long vacation and it was simply awesome. I'll publish some pictures of firearms that I took while I was visiting various places in Europe in a few days, after I do some editing. Until that happens, let's study how various firing mechanisms work, with the aid of some movies.

In today's post, we will look at an interesting movie about how semi-automatic and fully automatic weapons work. This movie was prepared by the US Army for training purposes sometime around the World War II period.

Note that this film depicts one way to achieve semi-automatic and fully-automatic fire. There are also other mechanisms, which we will study in subsequent posts.

Until then, happy viewing!

Exotic Firing Mechanisms: Electrical

One of the more exotic firing mechanisms around is the electrical firing mechanism. Mr. W.W. Greener, in his book, The Gun and Its Development, mentions an electric gun that was developed around the 1860s or so by "a French Baron living in Prague".

In this gun (which was a muzzle-loading weapon), a large bichromate battery A is stored in the butt of the gun. To remove the battery, one must remove the plug B and the heel-plate C at the end of the butt to access the battery. An induction coil D is connected to A to step up the voltage. Because the coil vibrates a lot during operation, a small magnet F is placed inside the coil to minimize the vibrations. When the user pulls trigger K, this causes the nut J to partially turn and withdraws the rod H to the guide L and comes to rest at stop O. The circuit at OPR is now complete and generates a spark which fires the priming charge, which in turn fires the main charge, which fires the weapon.

Another weapon invented by Henri Pieper of Liege, Belgium, also had an electrical firing mechanism. This weapon was a breechloader and was invented around 1883.

The user carried the batteries in the pocket of his coat. A special pad was fastened to the shoulder of the jacket or shooting coat of the user and this pad was connected to the batteries in the user's coat pocket. When the user placed the gun on his shoulder, a metal conductor on the heel of the rifle butt would contact the special pad and allow electricity to flow through the weapon. The cartridges of this weapon were also special as shown below:

Each cartridge was made of metal. To one side was a metal stud A, another metal contact point B, and a connection C made of thin wire, which connected A and B. Upon pulling the trigger of the gun, electricity flows from A to B via the wire C which sparks up and triggers the primer and thereby ignites the gunpowder. This weapon was claimed to have a battery life of two weeks and could fire about a 1000 shots before needing to recharge the batteries.

These weapons never really caught on because they could not provide a mechanism that was more reliable than a centerfire cartridge. Making the cartridges was also relatively more complicated. However, this wasn't the end of line for an electric firing mechanism.

With the advent of caseless cartridge technology, at least two different companies, Voere of Austria and Metal Storm of Australia, manufacture weapons that use electronic ignition systems. Another weapon is the Remington EtronX that uses centerfire cartridges with an electronic ignition system. This weapon has a couple of 9 volt batteries in the butt, that supply the current to fire the weapon.

Electrical systems haven't caught on much yet because of a number of reliability issues, e.g. what happens if the weapon is accidentally dropped into water. However, it has the advantage of reacting faster than mechanical systems, so some research does still continue in this area of technology.

Exotic Firing Mechanisms: The Gyrojets

In the world of firing mechanisms, one more development must be mentioned: The Gyrojet or rocket powered bullets. The Gyrojet family of small arms were conceived in the 1960s and a company called MB Associates (or MBA for short) developed a pistol, carbine and rifle using the principle of rocket propulsion.

Unlike conventional pistols, the gyrojet weapons didn't need as thick a barrel or firing mechanisms since the pressure on leaving the barrel was still relatively low. The ammunition consisted of a projectile with four tiny rockets placed at an angle off the center. Upon firing the four rockets, the projectile would spin about its axis and thereby achieve spin stability in the air. In a normal weapon, the bullet is at its fastest velocity just when it leaves the barrel and slows down as it travels in the air. In the case of a gyrojet round, the velocity builds up as it travels in the air. Hence, gyrojets were less lethal in close ranges, but got more lethal as it gained speed until the rockets burned out. In the case of gyrojets, the rockets would burn out approximately 60-70 feet outside the barrel and would reach a velocity of about 1250 feet-per-second at this point, after which the rocket propellant would run out and the bullet would travel under its own momentum. The accuracy was also better than conventional firearms over longer distances, because the trajectory of the round was flatter.

The firing mechanism of the gyrojet weapons was absolutely unique. Like a percussion firing mechanism, the rockets were ignited by a primer which was sensitive to percussion. Unlike a conventional weapon, when the trigger was pulled, a lever would strike the front of the bullet and push it backwards into a fixed firing pin. The force would ignite the primer, which would in turn ignite the four rockets and then the round would move forward.

Unfortunately, the gyrojet family of weapons never took off for a few reasons:

1. They were large caliber rounds and a new Gun law was passed in 1968 which classified Gyrojet bullets as "destructive devices" since they were explosive rounds greater than .50 caliber. This meant people had to pay extra taxes and get a special permit to own a gyrojet based weapon.
2. Didn't offer too much advantage over conventional weapons.
3. Bullets and the weapons cost much more.
4. Loading speed was much slower than conventional weapons

However, the gyrojet weapons were much lighter than their conventional prototypes since they didn't need to be built at strongly (as most of the acceleration happens after the round has left the barrel). Also, the barrel didn't need to be rifled, as the spin to the projectile was provided by the four off-center rockets.

Since Gyrojet weapons never became popular, manufacturing stopped in the late 1960s. Some weapons are still available as collector's items, but the bullets cost over $100 per bullet.

Percussion Lock or Caplock Mechanism

So far, we've covered firing mechanisms all the way to the flintlock. The flintlock was a major advancement in firing technology and it stayed active for over one hundred years. One of the disadvantages of it (and all previous technologies, the matchlock, snaplock, wheel-lock etc.) is that when firing the weapon, the basic principle in all these weapons is to light some gunpowder in a firing pan which is attached to the barrel, but located outside the barrel and have the pan connected to the main gunpowder charge inside the barrel by a touch hole. The flame first lights in the firing pan and then travels through the touch hole and lights the main charge of gunpowder, which then ejects the bullet. Because of this, there is a noticeable delay from when the flame lights in the pan to when the gun actually fires.

The next big advance was due to a Scottish clergyman, one Rev. Alexander Forsyth. The good clergyman was also an avid hunter and liked to go bird hunting in the marshes. While hunting, he noticed that the birds would often spot the flame from the pan and immediately change direction. Since there is a delay between when the contents of the pan light up and when the gun discharges, this delay was long enough for many birds to escape. Rev. Forsyth made several experiments and finally settled on using mercury fulminate as his ignition mechanism. His patent application (granted April 11th 1807) reads as follows:

"I do make use of some one of the compounds of combustible matter, such as sulphur or sulphur and charcoal, with an oxymuriatic salt; for example, the salt formed of delphlogisticated marine acid and potash (oxymuriatic of potassium), or of fulminating metallic compounds, as fulminate of mercury or of common gunpowder, mixed in due quantity with any of the aforementioned substances, or with an oxymuriatic salt as aforesaid."

The specification is pretty broad and doesn't reveal too much, so we'll study what this means. First, we determine what a fulminate is. Ordinary black gunpowder and some other explosive materials have the property that they may be ignited by striking them with some force between two metal faces. However, the resulting explosion doesn't provide any more force than if they were lit with a flame. A fulminating substance is one that is reliably ignited by percussive force and the resulting explosion is more energetic than if it were lit by a flame or by any other means. The most well-known fulminate is potassium chlorate. Some readers might have played with a roll-cap toy pistol as kids, where the tiny caps explode when struck under pressure. There are other fulminates such as mercury fulminate, silver fulminate, gold fulminate etc.

The earliest research into these substances was made by a Frenchman named Peter Bolduc, prior to 1700. There were several reports published between 1712 and 1714 by the Royal Academy of Sciences, of experiments by Nicholas Lemery. Bayen, the chief physician of King Louis XV discovered mercury fulminate in 1774, Fourcroy studied them in 1785, Vauquelin in 1787, and Berthollet discovered silver fulminate in 1788. Until then, no one thought of using fulminates to firearms. The first few experiments by Berthollet ended in failure because the material was deemed too sensitive and he finally gave up after a couple of close calls. An Englishman named Howard invented a new priming gunpowder in 1800 using the research of Fourcroy and Vauquelin, but it was also not too popular. Finally, it was left to Rev. Forsyth to make the necessary discoveries and get the patent. In his patent application, he also reveals his firing mechanism:

"Instead of permitting the touch-hole, or vent, of the species of artillery, fire-arms, mines etc. to communicate with the open air, and instead of giving fire by a lighted match, or flint or steel, or by any other matter in a state of actual combustion, applied to a priming in an open pan, I do so close the touch-hole or vent by means of a plug or a sliding-piece as to exclude the open air, and to prevent an sensible escape of the blast, or explosive gas or vapour, outwards, or from the priming or charge; and, as much as it is possible, to force the said priming to go in the direction of the charge, and to set fire to the same, and not to be wasted in the open air."
The basic idea of his patent ran like this:

Public domain image courtesy of wikipedia

It consists of a small metal nipple sticking out in the back of the barrel, with a hole that leads into the barrel. The main charge of gunpowder is loaded into the barrel. To the nipple is placed a small copper cap containing a percussion sensitive explosive such as mercury fulminate or potassium chlorate. The hammer is pulled back against spring pressure. When the trigger is pulled, the hammer is released and hits the copper cap covering the nipple with sufficient force to detonate the mercury fulminate (or potassium chlorate or whatever). The flame from the resulting explosion travels into the barrel and ignites the main gunpowder charge.

With this invention, there is very little delay from when the trigger is pulled to when the gun discharges. It is also not affected by weather and was more reliable than some of the previous systems. While Mr. Forsyth did get his patent and win a significant case of patent infringement in 1819 (Forsyth vs. Reveire), he did not pursue his invention very further and went back to his pastoral duties in his church. As a result, some manufacturers found creative ways to evade his patent and others waited for his patent to expire before making weapons that used this system.

Future firing mechanisms such as cartridges also use this same basic idea (i.e.) use a tiny amount of pressure sensitive explosive to detonate the main charge of explosive. In fact, this principle is still used in the majority of weapons to this present day.

The Flintlock

The flintlock was the next big advance in firing mechanisms. The flintlock was based on a Spanish invention called the miquelet lock. The flintlock took its ideas from the snaphaunce lock, which was itself an improvement over the snaplock. In a flintlock, the pan cover and the steel plate (a.k.a, the "frizzen") are combined together.(public domain image courtesy of Wikipedia)

Like the snaplock and the snaphaunce, this weapon has a serpentine hammer, which has jaws at the end, to which can be screwed on a piece of flint. Like the other two weapons, it has a steel (called a "frizzen") facing the piece of flint. When the trigger is pulled, the flint strikes the steel and releases sparks. Here's where the flintlock's innovation comes in. The steel frizzen is shaped like the letter 'L'. The horizontal part of the 'L' covers the firing pan where the priming gunpowder is. So the flint on the falling hammer strikes the frizzen and causes sparks of hot steel to form. As it is falling, it also pushes the frizzen away from the flint, thereby opening the pan cover and exposing the pan's contents. So the generated sparks will fall into the pan and light the priming powder that is in the pan.

If all goes well, the priming gunpowder in the pan will light. There is a tiny hole in the pan that leads to the main charge of gunpowder in the barrel. The flame will travel through this tiny hole and light the main charge and the weapon discharges. If all doesn't go well, the sparks may not fall into the pan, or the powder in the pan may light, but doesn't light the main charge. This is called a "flash in the pan", i.e. a flashy initial start, but no results.

The advantages of this weapon over its predecessors are many:

1. Unlike the matchlock, this weapon doesn't require the user to carry an lit match at all times to discharge the weapon. Hence it is much safer to use, especially in larger groups of soldiers or near gunpowder supplies. It can also be used more reliably in rainy weather.
   
2. The mechanism is not as expensive to manufacture as the wheel-lock and doesn't require as much specialized metallurgical and mechanical knowledge to manufacture.
3. Unlike the snaplock, the cover for the pan opens automatically when the trigger is pulled. Hence it is possible to carry the firearm loaded in damp conditions and not worry about the gunpowder getting wet, as the pan cover opens right as the sparks are generated.
4. Unlike the snaphaunce, there are fewer parts in this firing mechanism, as the pan cover and the steel are the same part. Hence, this leads to better reliability and less cost.

To load a flintlock, one would first fill the barrel with the main gunpowder charge and bullet. Then, the user would position the hammer at half-cock, i.e. they would pull the hammer back against spring pressure to a position called "half-cock" which was a "safe" position from which the hammer would not normally spring back. Then the user would pull back the frizzen cover and load the pan with priming powder and close it. Finally, the user would pull the hammer back to its full extent (i.e. full cock position) and the weapon would be ready to fire.

While the half-cock position was supposed to be "safe", sometimes a faulty safety mechanism would release the hammer from this position and it would strike the frizzen. Striking the frizzen from the half-cock position wasn't supposed to have enough force to cause sparks to form, but occasionally this would happen and the weapon would discharge. This is the origin of the modern-day phrase "going off half-cocked", which means "to take a premature action".

Flintlocks stayed with us for a very long time. The mechanism was invented in the 1600s and was used till at least 1850 or so. Some flintlock weapons are manufactured even in this present day, for hunting enthusiasts who prefer to use black-powder weapons.

The Snaphaunce

The next development from the snaplock was called the Snaphaunce. The origin of the name is believed to have come from Dutch Snap Haan which means "pecking cock". It was somewhat similar to the snaplock, but it borrowed one feature from the wheel-lock. Remember that we said, for the snaplock, one needed to open the firing pan's cover by hand before firing the weapon. With the snaphaunce, there was an additional mechanism connected to the trigger so that it would slide back the pan cover and expose the priming gunpowder automatically, as the trigger was pulled.

This meant that a person could walk around with a loaded weapon in damp conditions and keep the powder dry, as the pan cover would open just before the gun was about to be fired. These weapons were commonly used by thieves and highwaymen, as they were cheaper to manufacture than the wheel-lock, but didn't share the matchlock's weakness of having a fire lit at all times.

The Snaplock

Due to the price of the wheel-lock mechanism, it was generally only popular among the elites of society and among people who were close to major clock-making centers and had access to the materials and technologies needed to construct one. For instance, wheel-lock mechanisms never really caught on in Russia, China, India or most of Asia in general. The matchlock was still the weapon of choice for the common soldier due to its lower price and simplicity of construction.

However, there was still a need to develop a more reliable ignition system than the matchlock, but without the huge price of a wheel-lock mechanism. That need was fulfilled with the invention of the snaplock system in the late 1540s in Southern Germany.

This system consists of an S-shaped "cock" as seen on the left with a clamp on top with two jaws. The name "cock" is because it historically strongly resembled the head of a rooster. In other countries, the shape resembled a dog's head more and therefore is called a "dog" in some languages. In between the jaws is held a piece of flint, which is screwed on between the jaws. To the right of the mechanism was a steel plate (simply called the "steel" or later, "frizzen"). To prepare the weapon to fire, one would move the cock back under spring pressure (so called "cocking the weapon"). One would then position the steel plate so that it was over the pan (the pan is in the middle of the picture above). Upon pulling the trigger, the cock snaps forward with great force due to the spring pressure. The flint piece comes in contact with the steel plate and strikes it hard. The force of this drops hot steel sparks into the pan. The pan contains some priming gunpowder and a tiny hole that leads to the main gunpowder charge in the barrel.

If everything works right, the falling sparks ignite the gunpowder in the pan which burns first and the flame travels through the hole and ignites the main charge in the barrel, which discharges the weapon. If everything doesn't go to plan, no sparks may be generated or sparks may be generated and not fall into the pan or the powder in the pan may burn without igniting the main charge in the barrel (the classic "flash-in-the-pan", a strong flashy start initially with no result).

Like the matchlock, the snaplock sometimes had a cover over the pan to protect the priming gunpowder from adverse weather. Right before using the weapon, the gunner would slide the cover out of the way manually and then fire the weapon.

The resulting mechanism was a lot cheaper to manufacture than the wheel-lock. Like the more expensive wheel-lock, a snaplock weapon could be carried around with the weapon cocked and ready to fire at a moment's notice. The delay between pulling the trigger and the weapon firing was longer for a snaplock and it also had a higher rate of misfire than a wheel-lock. So for those who could afford it, the wheel-lock was still considered a more dependable choice. For the military exchequer who purchased weapons in the thousands, the matchlock was priced lower and hence the common soldier was still supplied with matchlocks. The people who really used the snaplock were mounted knights who wanted cavalry pistols. Hence it didn't see as much widespread use as the matchlock and didn't really catch on until the 1600s.

Even though it didn't see as much widespread use as the matchlock, it was the snaplock that influenced the design of other later firing mechanisms, the Spanish lock (miquelet), the snaphaunce lock, the English lock and later, the flintlock. These mechanisms will be discussed in the following articles. Due to the development of these more reliable firing mechanisms, the snaplock was considered obsolete and a peasant's weapon by the 1640s and fell out of fashion in most of Europe, except in Russia.

The Wheel-lock

In some of the previous posts, we've discussed matchlocks in detail. One of the major problems of a matchlock is keeping the slow match lit during damp conditions. Another problem is that it is easy to determine the position of a matchlock man in the dark, since the flame from the slow match gives away his position. This second issue is not a problem for large groups of men, but is a problem for individuals who wish to stay concealed.

It is not surprising then that after the wheel-lock was invented, it was quickly adopted not only by sportsmen and hunters, but also by highwaymen and burglars. The technology behind the wheel lock is similar to cigarette lighters and the clockwork wind-up cars that were common during the 1950s to the 1970s. The wheel-lock was first invented in the Nuremberg area of Germany in 1517.


It consists of a steel wheel A which has a serrated edge and a serpentine arm B. On the end of the serpentine arm is a jaw mechanism. As you can see above, there is an item (marked in dark gray) held between the two jaws and the screw around the jaws is tightened so that the item is held in place. This dark gray item is a small piece of iron pyrite. The serpentine arm itself can be placed in two positions. In the first position, the serpentine is moved so that the iron pyrite piece is not touching the wheel and it is in the "safe" position". When it is ready to use use, the serpentine arm is moved so that the iron pyrite piece touches the wheel A and the arm is held in place under spring pressure. The wheel itself is attached to a round mainspring (like the kind used in old wind-up clocks and watches), which is wound tightly using a key. When the trigger is pulled, the wheel is released and spins round and sparks fly from the iron pyrite piece (similar to a modern cigarette lighter). Some sparks will fly on to the pan that is just under the pyrite piece and light the priming gunpowder in there. There is a tiny hole in the pan that leads to the main charge of gunpowder in the weapon's barrel. If all goes well, the gunpowder in the pan burns and the flame travels through the hole in the pan and ignites the main gunpowder charge in the barrel, thereby discharging the weapon. If all does not go well, only the gunpowder in the pan burns and therefore you get the classic "flash-in-the-pan" i.e. a spectacular start, but no results.

To make sure that the priming powder does not get wet in the rain, the trigger mechanism is also sometimes attached to the pan cover. In some models, pulling the trigger does two things simultaneously:

1. Release the wheel so that the unwinding mainspring will rotate it.
2. Slide open the pan cover so that the gunpowder (priming powder) is exposed.

This mechanism has quite a few advantages over the old matchlock:

1. It isn't affected by the weather.
2. With a matchlock, the user to keep paying attention to the match to make sure it is lit. This is not needed with a wheel-lock
   
3. There is less danger of igniting a neighbour's powder supply by accident.
   
4. One can leave a loaded wheel-lock pistol wound up and ready to use at a moment's notice.

On the other hand, constructing a wheel-lock requires knowledge in metallurgical techniques such as the ability to make a spring that can be wound up and clock-making technologies in general. So it is no surprise to discover that Nuremberg was also a big clock-making center around the time the wheel-lock was invented (some people even credit a Nuremberg watch maker by the name of Peter Henlein with inventing the first mechanically driven pocket watch).

In the 1500s, clock-making technology was strictly guarded by certain guilds and thus, wheel-locks mechanisms were more expensive to manufacture than matchlocks. There was also the problem of somewhat unreliable springs in early models, but this problem was quickly solved. Maintenance of the parts also required a skilled gun-maker who was familiar with clockwork mechanisms as well.

Due to the cost of manufacturing, wheel-locks were not as widespread as matchlocks. However it was more convenient to use on horseback and also by rich hunters. Soldiers who were in charge of guarding the gunpowder also preferred wheel-locks, since it didn't have a lit fire source unlike the matchlock. Thus there wasn't a danger of lighting the gunpowder supply by accident.

Robbers and highwaymen also quickly adopted it because it allowed one to carry a concealed weapon. It was also popular with assassins for the same reason and thus it was banned by several European city-states and throughout the Holy Roman Empire. By 1532, the Nuremberg city council complained that although law-abiding citizens were not allowed to own wheel-lock handguns, highwaymen and robbers all carried them, so that the law was unenforceable.

Matchlocks

In our previous discussion that covered some early portable firearms, we've seen how the early firearms were used by soldiers. To recap, they would hold the weapon with both arms and try to manipulate a lit rope (a slow match) with the tips of their fingers towards a touch hole on the side of the barrel, while still holding the weapon with their hands. Needless to say, the technique was extremely cumbersome and prone to inaccuracy. Hence, one of the first major developments in small arms history was the invention of the matchlock.

As far as firing mechanisms go, the idea of using a trigger to activate a weapon was not a new invention, as they had been used by crossbows in centuries before. So it was only logical that the idea would be borrowed for firearms as well.

Part List:

• A - Flash pan cover
• B - Flash pan (with touch hole)
• C - Serpentine (or cock)
• D - Trigger
• E - Slow match (i.e. a lit rope)
• F - Sear
• G - Pivot
• H - Flat spring
• I - Tumbler link
• J - Barrel
• K - Lock plate
  

The soldier would load the barrel with gunpowder and a bullet. Then, they would pour a little extra powder into a flash pan (part B in the picture). The flash pan has a tiny touch hole leading into the main gunpowder charge inside the barrel. Many rifles featured a cover on top of the flash pan, so that they could keep the powder in the flash pan safe from the elements, until the moment of use. A slow match (E) would be attached to a curved lever called a Serpentine or a Cock (because it resembled a rooster's head in some early weapons). You can see the serpentine labelled as C in the above figure. The trigger D is connected to a sear lever F, which is connected to a tumbler link I. When the trigger is pulled, the serpentine C is pulled towards the flash pan B and lights the gunpowder charge in the flash pan. This in turn burns through the touch hole and ignites the main charge inside the barrel. A flat spring H is used to return the sear lever back to its normal position.

You can see an animation of the mechanism working below (if you cannot see the animation running below, click on the image and it will open into a larger window that shows an animated image):

This was the first real firing mechanism used in small arms. It wasn't always reliable though - many a time, the gunpowder in the flash pan could be blown off or become wet in the rain, or the slow match could go out. As a precaution against the rain, the slow match rope would be lit on both ends, so that if one end went out, it could be re-lit from the other end. Sometimes when the trigger was pulled, the contents of the flash pan would ignite, but it wouldn't burn through the touch hole and therefore fail to ignite the main gunpowder charge inside the barrel. Such a phenomenon was called a flash in the pan. This phrase is still part of the English language and now means "something which starts off initially very bright and showy, but soon fails to deliver anything of value."

Disadvantages

1. It was difficult to use in wet weather because of the problems of the powder in the pan getting damp and the slow match going out in heavy rains.
2. It was quite dangerous to have around large quantities of gunpowder. For instance, when a group of soldiers were loading their weapons from their powder horns (i.e. a large container that hangs from the waist and carries extra gunpowder), there was always a chance that the open flame from one person's matchlock could set off another person's supply.
3. Since the slow match was always lit, the glow could give away a person's position at night time. The slow match also had a pretty distinct smell that could let people know that a person carrying a matchlock was nearby.
   

Nevertheless, matchlock technology stayed alive for a very long time. The Janissary troops of the Ottoman empire were using these weapons in the mid 1400s. By 1526, they were introduced into India by the invasion of Babur, the first Moghul ruler of India. In 1543, a Portuguese vessel was wrecked off Tanegashima island in Japan and some of its crew showed the local Shogun their matchlock weapons, which the Japanese were very quick to clone and use for their own local wars. Well into the 19th century, matchlock weapons were still being used in India, China and Japan. There were even some records of rebels using matchlocks in East Timor well into the 20th century.