Cartridge (firearms)
From left: .50 BMG, .300 Win Mag, .308
Winchester, 7.62x39mm, 5.56x45mm NATO,
.22LR.
A cartridge, also called a round, packages
the bullet, gunpowder and primer into a
single metallic case precisely made to fit the
firing chamber of a firearm. The primer is a
small charge of impact-sensitive chemical
that may be located at the center of the case
head (centerfire ammunition) or at its rim
(rimfire ammunition). Electrically-fired cart-
ridges have also been made. Caseless am-
munition has been made as well. A cartridge
without a bullet is called a blank; one that is
completely inert is called a dummy.
Design
The cartridge case seals a firing chamber in
all directions except down the bore. A firing
pin strikes the primer, igniting it. The spark
from the primer ignites the powder. Burning
gases from the powder expand the case to
seal against the chamber wall. The projectile
is then pushed in the direction that releases
this pressure, down the barrel. After the pro-
jectile leaves the barrel the pressure is re-
leased, allowing the cartridge case to be re-
moved from the chamber.
Automatic
and
semiautomatic
firearms,
which
extract
and
eject
the
case
.30-06 Springfield cartridge specifications.
This is a rimless cartridge case. Measure-
ments are in inches.
An M4 Carbine, with an ejected case visible
in mid-air.
Various cases of assorted common calibers.
automatically as a part of their operation,
sometimes damage the case in the process of
ejection. Brass is a commonly used material,
From Wikipedia, the free encyclopedia
Cartridge (firearms)
1
Aluminum .44 caliber cases.
as it is resistant to corrosion and ductile
enough to be reformed and reloaded several
times. However, some low-quality "plinking"
ammunition, as well as some military am-
munition (mainly from the former Soviet
Union and China) is made with steel cases
because steel is less expensive than brass. As
militaries typically consider small arms cart-
ridge cases to be a disposable, one-time-use
affair, the lack of ductility is inconseq