How Flintlock Guns Work

Guns have been around for an incredibly long time, and they started with the cannon. The World Book encyclopedia discusses the first significant use of a cannon at around 1350 AD, making it one of the oldest pieces of modern technology still in use.

A cannon is a remarkably simple device. It consists of a strong metal tube with a plug at one end. There is a small hole for a fuse drilled through the tube. You load gunpowder into the tube from the open end of the cannon and then insert a cannon ball so that the gunpowder and ball are pressed against the plugged end. You stick a fuse in the small hole and light it to ignite the gunpowder (or you can pour a little gunpowder in the hole and light the gunpowder instead of using an actual piece of fuse). The explosion shoots the cannonball away from the cannon at high speed.

­The first guns were essentially hand cannons -- small tubes that the user loaded with gunpowder and a ball and lit from the outside. Around 1400, hand cannons were fairly common, and people were even using four-barrel hand cannons! You loaded each little cannon separately and lit each one when you needed it.

The hand cannon required two technological improvements to make it into a useful tool:

A lock is the ignition mechanism for a gun, and several locks preceded the flintlock. For example, the matchlock was simply a piece of slow-burning rope that you would light ahead of time and then move into position to light the gunpowder. The slow-burning rope was attached to a lever that you moved with your finger to rotate it into position -- the first trigger. Obviously, the matchlock had several problems:

Despite these problems, matchlocks were common for 200 years because they were a better option than lighting the gunpowder by hand and they were cheap to build.

What the world needed was a way of igniting gunpowder in the barrel of a gun that was instant, reliable and fairly weatherproof. It also needed to be relatively inexpensive and easy to make. The flintlock was the technological marvel that solved all of these problems!

The Merriam Webster Dictionary describes a lock, in the context of a gun, as "The method for exploding the charge or cartridge of a firearm."

The flintlock is the most venerable of the lock technologies. The flintlock mechanism, like the pendulum clock mechanism, is amazing from an innovation standpoint. This single device solved so many of the problems of the time, and it did so using the fairly primitive tools and technology already available then. The flintlock was quite an accomplishment!

The basic goal of the flintlock is simple: to create a spark that can light the gunpowder stored in the barrel of the gun. To create this spark, the flintlock uses the "flint and steel" approach. The idea behind flint and steel is straightforward. Flint is an amazingly hard form of rock. If you strike iron or steel with flint, the flint flakes off tiny particles of iron. The force of the blow and the friction it creates actually ignites the iron, and it burns rapidly to form Fe₃O₄. The sparks that you see are the hot specks of iron burning! If these sparks come near gunpowder, they will ignite it.

The flintlock therefore needs:

The flint needs to move at high speed and strike the steel in such a way that the sparks fall into some gunpowder. You can see the four parts that make this happen in the picture below.

The main parts of a flintlock are:

You can see these parts labeled in the picture below.

These four pieces are all that the flintlock actually needs to accomplish its goal, but all flintlocks also solve the problems of loading the pan, protecting the pan from the weather and triggering the hammer, so there are three additional parts:

The mainspring presses against the tumbler and is able to rotate the hammer with a great deal of force. The sear engages the tumbler when the gun is cocked and holds the force of the mainspring. When you pull the trigger, it pushes the sear enough to release the tumbler and allows the hammer to drive the flint forward. You can see all of these parts in the image below.

When you work with a flintlock and watch a flintlock in action you can see how all of these pieces work together. A flintlock has three positions for the hammer: uncocked, half-cocked and fully cocked.

In the fully cocked position, the gun is ready to fire. If the trigger moves the sear just a bit, it releases the tumbler. In the half-cocked position, you can load the gun. The trigger is locked in the half-cocked position and cannot release the tumbler. After you fire the gun, it is in the uncocked position. The following images show you these three positions from both sides of the lock, which allows you to understand how the sear and tumbler work together:

Note how the shape of the tumbler locks the half-cocked position:

In addition, the frizzen has the ability to move. In the cocked position the frizzen is down, covering the pan. When the flint strikes it, the frizzen pops out of the way to expose the pan. The frizzen spring holds the frizzen in both positions.

To use a flintlock, you follow these steps: (see the links at the end of this article for much more detailed instructions):

When you fire the gun, the flint strikes the frizzen and shaves off iron to create sparks. The hammer's blow also snaps the frizzen back to expose the gunpowder in the pan. The pan's gunpowder ignites, and it flashes through a small hole in the side of the barrel to ignite the gunpowder inside the barrel. The gun fires!

Videos!

These three videos let you see and hear the flintlock in action:

The barrel of a flintlock is its own technological marvel, especially for the time. A blacksmith would take a flat piece of iron and beat it into a cylindrical shape around a mandrel -- a long rod of the proper diameter. By heating the iron to a high enough temperature in a forge, the blacksmith actually welded the seam along the length of the barrel to form a strong tube. This process could take days. Barrels ranged anywhere from pistol length (6 to 12 inches, 15 to 30 cm) to long gun length (40 to 60 inches, 102 to 152 cm).

The blacksmith could finish the interior of the barrel as either a smooth bore or a rifled bore. A smooth bore is just that -- smooth along the entire length of the barrel. The Brown Bess of the American Revolutionary War was smooth bored. So is any shotgun. Drilling out the tube with successively larger bits and then polishing with a reamer creates a smooth bore barrel.

Rifling a barrel is a way of increasing the accuracy of the bullet, whether the bullet is spherical or cone shaped. To rifle a barrel, you start with a smooth bore and engrave spiral grooves down the inside of the barrel. A typical pattern is one twist of the grooves in 48 inches (122 cm) of barrel length. As the bullet speeds down the barrel it engages the grooves, exiting the barrel with a rapid spin (between 1,000 and 3,000 RPM) and traveling at a speed of 1,000 to 2,000 feet per second (305 to 610 meters per second) through the air.

Once the barrel is smoothed or rifled, one end is closed off with a breech plug. Then, a small hole is drilled in the barrel to allow the flame from the flintlock's pan to enter the barrel and ignite the charge.

The expression "lock, stock and barrel" goes way back, and is directly related to the manufacture of guns. To assemble a complete gun you need all three parts:

If you have all three parts, you can assemble a complete gun. In colonial America, a person wanting a gun might have gone to a gunsmith for a complete firearm, or might have purchased the barrel and lock and created the stock him- or herself.

The stock is a fairly intricate piece of carving. It has to accept the barrel, the lock, the trigger and the trigger guard. In the following two pictures you can see the necessary woodwork, and you can also see how the trigger and the lock fit together in the stock.

When you pull the trigger, the piece of metal within the stock pushes upward against the sear pin and releases the tumbler so the hammer falls.

A complete gun also included several decorative brass fittings for the nose and the butt of the gun, as well as a ramrod and a ramrod holder underneath the barrel.

The main challenge in assembling the gun, besides the obvious woodworking talent necessary to carve the stock, is getting everything to line up. The barrel has a hole in its side and the pan of the flintlock must align perfectly with it.

The hole in the barrel is tiny. It is hard to see in the picture above, but it is in the middle of a screw-in piece of this modern flintlock reproduction.

Flintlocks lasted a remarkably long time, but they were eventually replaced by a lock and ignition system called the percussion cap. The percussion cap was easier to load, more weather resistant and more reliable, so by the time of America's civil war, both Union and Confederate armies used percussion-cap guns exclusively.

The percussion cap was made possible by the discovery of a chemical compound called mercuric fulminate or fulminate of mercury. Its chemical formula is Hg(ONC)₂ -- it is made from mercury, nitric acid and alcohol.

Mercuric fulminate is extremely explosive, and it is shock sensitive. A sharp blow, or even too much finger pressure, can cause it to detonate. By putting a small amount of mercuric fulminate in a pre-made cap (a tiny cup about the size of a pencil eraser) and affixing the cap to a nipple and tube leading into the barrel, the cap can ignite the gunpowder in the barrel.

The transition from flintlock to percussion cap is very minor, and many flintlocks were converted. The percussion lock is exactly the same as the flintlock in terms of the mainspring, hammer, tumbler, sear and sear spring. The hammer has uncocked, half-cocked and fully cocked positions just like the flintlock.

What the percussion lock does not have is the flint and frizzen. Instead, there is a nipple that accepts the cap, and this nipple contains a tube that leads the flame from the cap down to the main charge of gunpowder in the barrel. The hammer is shaped to strike the cap on the nipple and cover it so the nipple does not get blown off. These pictures help you understand the percussion lock:

The percussion lock did not last very long -- perhaps 50 years. Manufacturing processes were developing rapidly at the time and it became possible to integrate the cap, powder and projectile into a single metal package at low cost. These bullets are what we use today!

For lots more information on flintlock guns and other weapons, check out the links on the next page.