Evening star. [volume] (Washington, D.C.) 1854-1972, 1930-08-01

fort, Va, September II, 1928, gaze
the tollotUing enHghtening talk on
the subject OF bdllistics.
BY COL. CALVIN GODDARD.
The science of forensic ballistics,
which is the matter which am here
to discuss, is based upon the simple
fact that it is impossible to produce
two things exactly alike, either by man
ual or mechanical means This holds
alike for two blades Of grass, two match
sticks or two gun barrels. It holds as
well for any other part Of the firearm.
Two barrels made in succession on the
same machine with the same tools will
have microscopic differences which
register on the bullets fired through
them. Each bullet through one barrel
will show certain characteristics; each
bullet through the next will show some
what different ones. Owing to this
happy fact it becomes possible for us,
given adequate equipment and expert
ence, to determine by studying a fired
bullet in comparison with bullet fired
experimentally through an arm under
suspicion, whether or not the first bull
let passed through that arm.
Shells can he identified as well by
reason of the marks left on their
primers by the firing pins, each of
which differs from every other even
though made consecutiyely, and by
certain other markings recorded on the
primers when they recoil against the
breach Of the arm at the moment of
firing. We thus have two means of
fastening upon any given gun the fact
that 1t has or has not figured in some
particular crime-namely, the exam
nation of the fatal bullet, the empty
shell or both in case both are available.
Tells of Experiment.
These may sound like extravagant
statements, but after the principles OF
the manufacture of pistol barrel, a
pistol firing pin or pistol breach have
been graphically portrayed to you, I
feel sure you will be convinced that
they are based upon fact and not upon
fancy. To demonstrate the fact bar
rels made in succession with the same
tools do differ. I made an experiment
when on duty at the Springfield Arm
DRY in 1926. This involved the manu-
facture Of six barrels in succession on
the same machines, four upon one ma
chine and two upon the adjoining.
When completed, these were assembled
into pistols, fired by another of1cer,
and the fired bullets caught in cotton
waste and recovered. Two bullets were
fired through each barrel and their
bases marked with identifying numerals
which signif1ed to the officer marking
them. but to no one else, which barrel
had fired each. The IL bullets were
given to me and returned them to the
officer firing them, matched into SIX
pairs according to the SIX barrels
through which they had passed, re-
ceiyinQ from him his aff1davit to the
effect that I had identified them cor
rectly, Since new barrels nave not &C
ouired the individual characteristics
which those long in use possess, 1t
evident that this is about as severe
test as could be undertaken.
Anart from identifying a bullet to
a given arm, we can, when presented
with a fired bullet of unknown origin,
identify the make of the arm which
fred it by a study of the groove marks
left upon it by the barrel through
which it passed. No two arms makers
employ rifiing Of the same character
istics, hence if we are familiar with
the types of rifling marks left by bar
rels of different makes, we can, by a
process of elimination, throw out all
the makes save the particular one
through which a certain unknown bull
let has passed.
A further step in identification con-
sists in determining the marker OF any
unknown fired bullet. This can be &C
complished by reason Of the fact that
no two manufacturing companies pro-
duce bullets of the same caliber and
type exactly alike. By having on hand
a reference collection Of unf1red bullets
in every caliber and type by every
known maker we are able to ascertain
by another process of elimination the
make of any unknown bullet submitted
for study.
Other information which we can
secure is made possible by the use OF
an instrument which We call helix
ometer, tiny perlScope which we nSerc
into a gun barrel to tell us whether 1t
has been fired since 1t was last cleaned;
II so, whether 1t was fired with black
or smokelesS powder and approximately
how long ago it was fired. Still further
interesting data may be uncovered by
study of unburned powder grains re-
moved from the body or clothing OF q
person shot at close range. These grains
differ in physical appearance according
to their manufacture, and in this way
single grain of powder may prove, when
its make is ascertained Of considerable
use in forging chain OF circumStantial
evidence.
Accurate bullet and shell identifica-
ton was only made possible in 1925 by
the adaptation of the comparison
microscope to the work by Mr.. D. o.
CraVelle OF South Orange, N. j. Prior
to that time, although many so-called
experts existed, bullet Identification was
pretty much hit and miss affair. In
support of my rather dogmatic state
ment on this point you may be interested
to know that the Bureau of Standards at
Washington has gone on record to the
effect that satisfactory bullet identiflca-
ton can only be accomplished with the
use of a comparison microscope.