A cartridge is made of four
pieces. The projectile, case, propellant and the primer.
The projectile is the piece
of the cartridge that leaves the gun when fired. The earliest projectiles
were made out of lead. They were easy and cheap to make. On the other hand
they foul the barrels and had problems with gripping the rifling at a higher
velocity, a thing that made the lead projectiles seldom went faster than 450
mps. To make the projectile better they made a jacket of metal around a
lead core instead. Today, all military ammunition has a full metal jacket
after a decision in the Haag conventions.
The jacket may be made of
Tombac (Tombac is an alloy between 90% copper and 10% zinc.)
Tombac plated steel.
Copper nickel platted steel.
(Copper nickel is a alloy between 85% copper and 15% nickel)
Copper nickel plated brass.
The best jacket is made
of Tombac. It can be made with very high precision and gives less wear
in the barrel then for example copper nickel plated steel. The drawback
is that Tombac is the most expensive of the materials here.
The core is cold pressed
and of led with ca 1-3% antimony. The antimony is to make the core harder.
The only change from this
is the 5,56x45 projectile that has a steel core in the front to give a
better penetration on hard targets.
The case has many functions.
It encloses the propellant, holds the projectile and the primer. It should
be formed so that it easily may be put in and pulled out of the chamber.
At discharge of a cartridge, the case expands out of the heat and pressure.
That means that the case seals of the chamber backwards so that gases don't
leak out, and all the effect may move the projectile forward. After the
firing the case shrinks back which means it is easy to extract from the
chamber again. It is almost always out of brass in the military. During
WW2 there where cases made out of brass plated steel too.
Gun powder is used as propellant
in the cartridge. The powder burns quickly and creates a high pressure
in the cartridge which pushes the projectile out of the barrel. The first
kind of powder was the black powder. It was out dated in the early 1900
in favor of the smokeless powder, which had better performance and storage
The primer is what makes
the powder to ignite. At a blow from the firing pin the primer bursts into
flame and ignites the powder. The primer used in the Swedish military
is almost always of the Berdan type. The exceptions I know about are the
.38 special and the .50 BMG that is of the Boxer type. The difference between
Berdan and Boxer is that the Boxer has an anvil mounted in the primer,
while the Berdan have the anvil turned out in the cartridge. The biggest
reason to use a Berdan is that it is cheaper to manufacture.
in .38 Special