Evening star., 1941-10-24
Word 'CaIiber' Gives
Recruits Trouble in
Identifying Guns
Official Designations
Offer Little Help in
Learning Weapons
BY EDWARD E. BOMAR,
The Stars Special News Service


Could the Army substitute more
accurately descriptive terms for the
overworked word "caliber," recruits
might have less trouble identifying
the principal guns.
As 1t is, about the only way to be
sure of the difference between
caliber 75-millimeter field gun and
.50-caliber machine gun, for in
stance, is through experience and
memory.
Fortunately the list of weapons
on which the Army mainly relies is
relatively brief. The guns official
designations, however, are likely to
be of little help in learning them.
A 50-caliber machine gun fires
cartridge exactly one-half inch in
diameter. But a huge coaStal-de-
fense gun which hurls l6-inch'
projectile weighing more than a
ton over the horizon also may be a
weapon of so caliber.
What Caliber Means.
The explanation is the word cali
Der has come to possess several
the French from the Italian about
the 10th century and subsequently
found its way into English.
Primarily, caliber means the in
side measurement of the bore, or di-
ameter, of a gun barrel, although
1t may just as well apply to ther-
mometer tube. Thus the familiar
French IS. an Army field artillery
standby since the World War, meas
ures exactly rs millimeters inside
its barrel, or approximately 90
inches.
Caliber has more specialized
meaning when applied to light
weapons. however. In this case 1t
refers to the fractional part OF an
inch, with no connection with the
French decimal system. Thus the
inside diameter of a .30-caliber
machine gun barrel measures ex-
actly 80 l-l00. or three-tenths, OF
an inch, as do the Garand and
Springfield rifles.
Because a fraction of an inch Is
involved. the decimal point is placed
before the caliber designations of
these light weapons, but omitted
when measurements are in milli-
meters.
Confusion Increased.
To add confusion, calber may
mean something entirely different
when referring to heavy guns. There
it is used as a term of measure
ment of the barrels length rather
than its diameter. Thus the tube
OF q 16-inch coastal defense gun OF
so calibers, measured internally from
breech TO muzzle, is so times its.
diameter, or 800 inches.
Regardless of the confusion, re-
eruits ordinarily become quickly IA
miliar with the principal guns. Most
of the weapons were in service In
the summer maneuvers.
They include:
l.-.30-caliber weapons - Spring
field rife and the faster-firing semi
automatic Garand rife; Browning
machine guns, both air and water
cooled, which are readily portable
and used by troops against enemy
personnel.
2.-.50-caliber weapons-Browning
machine gun, used both as an anti
tank and as an anti-aircraft weapon,
which shoots projectile somewhat
larger than the regular rife. Bullets
are either armor piercing or in
eendiary.
3-37-millimeter weaponS-Shoot
projectiles about an inch and . half
In diameter, weighing IA pounds.
These guns can be mounted in tanks,
used as anti-tank and anti-aircraft
weapons. and can be operated fast
with great accuracy.
80 and 81 millimeter mortars-
Used by infantry against both en-
emy troops and mater'iel. High
angle OF fire permits projectile to be
dropped behind hills and barricades
which protect against directly aimed
fire.
SIS -millimeter weapons-include
the field gun which fires q shell
weighing some. Is pounds, loaded
with either shrapnel, high explosive
or gas charges, and the howitzer,
which employs high-angle fire some
what like the mortar.
s-105- -millimeter howitzer-being
developed to replace 75-millimeter
guns as the principal light weapons
. Of the field artillery.
T-155- 5-millimeter weapons - in
eiude the field artillery guns, which
srs the largest weapons not on fixed
or railroad mountings, and the
howitzer, which can put large, high
explosive shells weighing some 95
pounds behind obstacles at great
distances.
Anti-aircraft weapons aside from
those used against low-fiying craft
include the present standard 3-inch
gun and the newer 90-millimeter
and also q still larger model than
the latter. which is just being de-
veloped,