Ballistic Substage for Quanta™ Series SEM - FEI Company

PRODUCT DATA
Any sample, all data
Simultaneous rotation of two objects
Rotation via SEM motor stage
Holder for cartridge cases and separate
holder for bullets
Easy mounting and handling
Fits 5-axis motorised stages
of Quanta 400 and 600
Ballistic Substage for
Quanta series SEM
Firearms identification
Forensic firearms examinations are based on firearms
identification. This involves the identification of a
bullet, cartridge case, or ammunition components
(GSR particles). Singular identification of bullets or
cartridges can be attributed to specific machining
processes of firearms.
Identifying features of fired ammunition (1)
When a gun is discharged, the grooves in the barrel
cause the bullet to spin as it travels the length of the
barrel and thus stabilise the bullet during flight. At
the same time, the expansion of the fired cartridge and
the high pressures propelling the bullet through the
bore of the barrel press and scrape the bullet against the
rifling as it heads toward the muzzle. As a result the
fired bullet will bear the negative impressions of the
grooves in a rifled barrel; these marks are described by
firearms examiners as land and groove impressions, or
lands and grooves.
In addition to the rifling marks produced on a bullet
by its passage through a gun barrel, a number of other
impressions found on cartridge cases and resulting from
machining processes are crucial to firearms
identification. Firing pin impressions, breechface marks,
extractor marks, ejector marks and chamber marks,
when present and of sufficient quality, are all features
used by firearms examiners in their analyses. During
the discharge of a firearm, the firing pin strikes the
primer of a cartridge, creating microscopic contact marks
and unique indentations. As the powder within the
cartridge begins burning, the cartridge case is propelled
backwards against the breechface with enough force to
be impressed with the characteristic microscopic features
of that surface.

PRODUCT DATA
Extractor and ejector marks are
produced when the cartridge case is
mechanically extracted from the
chamber and ejected and are visible as
fine striations and gouged impressions
on the rim and head of the case.
Chamber marks, parallel striations on
the cartridge case caused by contact
with the walls of the chamber of the
firearm, also occur at this time. All of
these potentially identifying features
are produced as a result of the
machining and finishing processes
of firearms manufacture, which
inevitably leave microscopically rough
areas and edges on the parts of a given
gun. During discharge, these
imperfections are transferred from the
metal parts of the firearm to the bullet
and cartridge case.
Examination
Traditionally, examination is done
using an optical microscope. Due to
lack of depth of focus optical
microscopes do not have the ability
to reveal fine detail seen at higher
magnification. The SEM has a far
superior depth of field. It can produce
images covering a wide range of
magnifications and depths on many
types of surfaces, including rough
and curved surfaces. Microanalysis is
also possible.
SK.1.R for cartridge cases SK.SB for bullets
Ballistic substage for FEI
Forensic SEM
A new ballistic substage is available
for FEI’s Quanta 400 and 600. This
substage (or “module”) is used for
rapid investigation of the surface, to
search for marks generated when the
bullet or slug passes through a gun
or pistol barrel. The specimen is
clamped between spring loaded
points. The module can hold two
bullets and/or cartridge cases for slow
rotation along their axis using the
motor stage of the SEM. Parallel
markings are at right angles to the
direction of the electron detector. In
this way, optimum contrast is
generated in secondary or backscatter
electrons, providing a tool for the
recording of characteristic patterns,
showing results which can correlate to
or exclude a given weapon.
Both objects will rotate together at
the same time. The SEM stage
software will store all stage positions,
including rotation, so comparison of
two objects is easy. The second object
is rotated and imaged live whilst
comparing to a frozen image of a
typical mark on the first object.
The rotation holder also fits
XL SEMs, equipped with a 5-axis
motorised 100x100 mm stage or
150x150 mm stage.
FEI Company
World Headquarters and
North American Sales
7451 NW Evergreen Parkway
Hillsboro, OR 97124-5830
Tel: +1 503 640 7500
Fax: +1 503 844 2615
e-mail: sales@feico.com
www.feicompany.com
Firing pin impression
Ejector mark
The ballistic substage may also be
used for other applications where
sample rotation along a horizontal
rotation axis is required. The rotation
holder consists of a module for
cartridge cases (SK.1.R), which is
driven by the telescope shaft of the
SEM and a module for bullets (SK.SB).
This kit can hold bullets of different
length.
(1) Firearms and Toolmarks in the FBI
Laboratory, Part 1, Sally A. Schehl, FBI,
Washington, DC
European Sales
Tel: +31 40 27 66 768
Fax: +31 40 27 66 786
Asia-Pacific Sales
Tel: +65 351 7671
Fax: +65 354 0644
©2002. We are constantly improving the performance of our products, so all
specifications are subject to change without notice. The FEI logo, The Structural
Process Management Company and ESEM are trademarks of FEI Company.
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032-DS00111 03/01
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