Bullet Construction and Manufacture
the manufacturer and caliber of a submitted bullet is an
important examination conducted in a forensic laboratory by
Firearm and Toolmark Examiners. We've discussed the
term "caliber on a previous page that can be found
There are a number of good reasons to
determine who made the bullet but one that stands out to be of particular
importance occurs when the bullet cannot be identified to a specific firearm
through normal firearm identification techniques. Let's say that several
shots are fired at a crime scene and all of the shooters are firing GLOCK brand
9mm Luger caliber pistols. In this situation all of the bullets collected
will have the same diameter and will have the same general rifling
The only way in this situation to determine
who may have fired one bullet vs. another is to look at the brand of ammunition
that each shooter was using (hopefully they used different brands!) and then try
to match the physical characteristics and materials to those used by one brand
cartridge or the other.
The fired cartridge cases collected at the
scene have headstamps that will identify who made the cartridge case, so once
they are identified to the gun they were fired from, we can look at the bullets
to see if they are similar to bullets made by those manufacturers.
By identifying the bullet manufacturer we can
now determine which gun most likely fired those bullets given the limited
universe of this one crime scene. Firearm examiners will examine the
unknown bullets and compare the physical properties of the bullets to known
standards. Through this process of direct comparison often times the
manufacturer can be determined and in doing so provide the investigation just
one more clue to help bring the case to a desirable outcome.
There are several things that firearm
examiners look for when they examine the bullets. The diameter and weight
are helpful in determining caliber, but the materials used and the
general shape of the bullet can assist in determining the manufacturer of
the unknown bullet.
Let's start with the materials used in
the manufacture of bullets.
Projectiles in general have come along way
over the last several centuries. What started out as crude rocks and
pebbles have steadily evolved into bullets born from very advanced engineering.
For some good information on the history of the bullet visit the
It wasn't until the late 15th century that
bullets were starting to be produced by casting metal into balls using molds.
The modern bullet can be manufacture through casting, swaging, milling, plating,
stamping or compression processes. These bullets are usually made of a single
solid metal alloy or a layered combination of various materials to
include lead, copper, brass, steel, and aluminum called jacketed
Solid Bullets- The most common
material used in the manufacture of solid bullets is lead. Lead bullets
are usually an alloy of lead and antimony which is added to give the bullet some
additional hardness. Variations are the norm when it comes to the
materials used in bullets and it's not uncommon to find lead bullets with a thin
coating of copper or brass plating. Bullets having this thin coating is
sometimes referred to as a copper-washed or "Lubaloy" bullet. This thin
coating can be easily scratched away from the surface of the lead causing
problems for firearm examiners when these bullets are damaged.
lead round-nosed bullet
Other solid bullets can be machined out of a
piece of copper, brass, or similar material. Newer manufacturing
techniques use pressure to compress a material like tungsten into a bullet
referred to as a "frangible" bullet. Examples of these can be seen below.
THV Solid brass
KTW Teflon coated
solid brass machined bullet
Jacketed bullets- Jacketed bullets are
a laminate of material, with the harder "jacket" covering a core typically made
of lead. This jacket material differs from the thin copper plating seen on
the copper-washed bullets above. The jacket material cannot be easily
The most common jacket material is copper but steel jackets are
widely used in bullets that originate in the European and Chinese markets.
Steel jacketed bullets are usually plated with a copper finish to help prevent
steel jacketed bullet
Almost all jacketed bullets contain lead in
their inner core but exceptions again exist and the most common example is the
7.62x39mm armor piercing bullet (show above right) that is steel jacketed, has a
thin layer of lead and a steel core. It is not uncommon for firearm
examiners to receive just the steel core as an exhibit. When this bullet
strikes a target the steel core can punch right through the nose of the jacket
material. I had a case several years ago where several of these bullets
were fired through the windshield of a car, killing the lone occupant. All
that was recovered from the victim were several steel bullet cores as seen
Steel cores from
steel jacketed bullets
Bullets may also contain material imbedded in
the hollow base of the
The lead bullets are typically associated with
revolvers and rimfire rifles where full-metal-jacketed bullets a most commonly
used in semiautomatic pistols and centerfire rifles.
Let's start with the general shape of
All bullet will generally fall into several
distinct shapes. These shapes are usually