There are two basic
types of handguns, the Revolver and the
Semi-Automatic.
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.
(Click HERE
for information about ammunition).
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 following diagram:
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.
