To understand how a revolver works, it helps to know something about
guns in general. Almost every gun is based on the same simple concept:
You apply explosive pressure behind a projectile to launch it down a
barrel. The earliest and simplest application of this idea is the
cannon.
A
cannon is just a metal tube with a closed end and an
open end. The closed end has a small fuse hole. To load the cannon, you
pour in gunpowder (a mixture of charcoal, sulfur and potassium
nitrate), and then drop in a cannonball. The gunpowder and cannonball
sit in the
breech, the rear part of the
bore (the open
space in the cannon). To prepare for a shot, you run a fuse (a length
of flammable material) through the hole so it reaches down to the
gunpowder. To fire the cannon, you light the fuse. The flame travels
along the fuse and finally reaches the gunpowder.
When you ignite gunpowder, it burns rapidly, producing a lot of hot gas
in the process. The hot gas applies much greater pressure on the powder
side of the cannonball than the air in the atmosphere applies on the
other side. This propels the cannonball out of the gun at high speed.
The first handheld guns were essentially miniature cannons; you
loaded some gunpowder and a steel ball and lit a fuse. Eventually, this
technology gave way to trigger-activated weapons, such as the
flintlock gun and the
percussion cap.
Flintlock guns ignited gun powder by producing a tiny spark, while percussion caps used
mercuric fulminate,
an explosive compound you could ignite with a sharp blow. To load a
percussion-cap gun, you poured gunpowder into the breech, stuffed a
ball in on top of it, and placed a mercuric fulminate cap on top of a
small nipple. To fire the gun, you cocked a hammer all the way back and
pulled the gun's trigger. The trigger released the hammer, which swung
forward onto the explosive cap. The cap ignited, shooting a small flame
down a tube to the gunpowder. The gunpowder exploded, launching the
ball out of the barrel. (Check out
How Flintlock Guns Work for more information on these weapons.)
In the 1800s, the percussion-cap gun slowly gave way to the revolver,
which only had to be reloaded every five or six shots instead of after
each shot. In the next section, we'll see how this system works.
The first revolvers used gunpowder, balls and caps like the earlier
percussion-cap pistols. The shooter would load each of the six chambers
in the cylinder with gunpowder and a projectile, and place separate
percussion caps on corresponding nipples. While the loading procedure
was tedious, a shooter could have six rounds fully prepared ahead of
time.
In the 1870s, these models were replaced by revolvers that used
bullet cartridges
instead of gunpowder and caps. Cartridges are a combination of a
projectile (the bullet), a propellant (gunpowder, for example) and a
primer (the explosive cap), all contained in one metal package.
In a modern revolver, cartridges are loaded into six chambers, each of
which can be positioned in front of the gun's barrel. A spring-loaded
hammer is positioned on the other side of the cylinder, in line with
the barrel. The basic idea of the gun is to cock the hammer back, line
up a new cartridge in between the hammer and the barrel and then
release the hammer by pulling a trigger. The spring throws the hammer
forward so it hits the primer. The primer explodes, igniting the
propellant, which drives the bullet down the barrel.
The inside of the barrel is lined with
spiraling grooves,
which spin the bullet to give it stability. A longer barrel improves
stability, since it spins the bullet for longer. Extending the barrel
also increases the speed of the bullet, since the gas pressure
accelerates the bullet for a longer period of time.
In early revolvers, a shooter had to pull the hammer back
before each shot and then pull the trigger to release the hammer. In
modern revolvers, simply pulling the trigger will force the hammer
backward and then release it.
You can see how a modern revolver works in the diagram below.
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Click on the trigger to fire the gun.
The sequence of events in each shot is very simple:
- The trigger lever pushes the hammer backward.
- As it moves backward, the hammer compresses a metal spring in
the gun stock (the handle). The diagram above shows a coiled spring;
uncoiled tension springs are also used in revolvers.
- At the same time, a pawl attached to the trigger pushes
on a ratchet to rotate the cylinder. This positions the next breech
chamber in front of the gun barrel.
- Another pawl lodges in a small depression on the cylinder. This
stops the cylinder in a particular position so it is perfectly lined up
with the barrel.
- When the trigger lever is pushed all the way back, it releases the hammer.
- The compressed spring drives the hammer forward. The firing
pin on the hammer extends through the body of the gun and hits the
primer. The primer explodes, igniting the propellant.
- The propellant burns, releasing a large volume of gas. The gas
pressure drives the bullet down the barrel. The gas pressure also
causes the cartridge case to expand, temporarily sealing the breech.
All of the expanding gas pushes forward rather than backward.
- To reload the gun, the shooter swings the cylinder out and pushes on the ejector rod to operate the extractor in the middle of the cylinder. The extractor grabs the base of the spent shells and removes them from the cylinders.
- To reload, the shooter can place individual cartridges into the chambers or load six at once with a speed loader (basically, a small metal holder with cartridges secured in the right position).
In double-action revolvers, the shooter can either pull the
trigger to cock and fire or pull the hammer back ahead of time. The
advantage of cocking the hammer first is that the trigger moves more
easily when it is time to fire.
Obviously, a revolver is easier to use than a flintlock or a
percussion-cap weapon. A shooter can load six shots at a time and only
needs to pull the trigger to fire. But revolvers seem very limited next
to newer technologies: The shooter must pull the trigger for every shot
and stop to reload regularly. On the battlefield, the revolver can't
possibly stand up to modern automatic weapons.
To Bear Arms
To learn about the gun laws in your area, as well as pending legislation, check out Gun Laws, Gun Control & Gun Rights.
The enduring popularity of revolvers is due to the simplicity of their
design. Everything fits together so well that the guns very rarely jam.
And since they are made with a relatively small number of parts, they
are relatively inexpensive to manufacture. For the home defender and
criminals alike, it is an ideal, affordable weapon.
For more information on revolvers and other weapons, check out the links on the next page
and that my friends, is how the gun was fired to kill these two, unfateful men.