The Arizona sentinel. [volume] (Arizona City [Yuma], Yuma County, A.T. [Ariz.]) 1872-1911, 1885-10-10
GUN MAl,...G.
An Art Which Is tho Refinement of the
Machinists' Trade.

Machinists' Trade.
Few people have any very accurate
idea of what modern steel riied cam
non looks like, or how complex and
difficult process its fabrication is.
To the average citizen the word big
gun suggests huge mass of cast iron
with a large hole in it-short. cum.
brous and ungainly. But the modern
steel gun is neither. On the contrary,
it is the work of art. and. being so, is
a thing of beauty. 1t begins with what
is known as the "tube, which is the
only portion of it that extends in an
unknown mass the entire length of the
gun. This tube is the foundation of
the structure.
After being forged to the required
length and rough diameter, it is bored
and turned with the nicely of the most
delicate machine. 1t is then ready to
receive what is called the Jacket. +"
This is another tube of forged steel.
large enough for the breech, and of the
original tube to be inserted in it for
about one-third of the length of the
latter, measuring from the breech for
ward. In preparing the jacket for the
insertion of the tube, the two are so
fitted that the bore of the former is a
few thousandths of an inch smaller
than the exterior of the latter. The
jacket is then heated to a black heat.
by which it is expanded sufficiently to
admit the tube, and its shrinkage VIII 10
cooling forms a ''cold well" and pro-
vides what is termed in the
technology of gun-making the re-
quired initial tensions that is to say,
the exertion of a constant pressure by
the jacket upon the walls of the tube
within. 1t usually happens that the
compression produced by the shrinking
process is so enormous as to contract
the bore of the original tube. under the
length of the jacket. sufficiently to re-
quire the boring head to be run through
again in order to make it uniform.
After the jacket has been shrunk on
the surface it is again turned and pol
ished with mathematical precision.
Over this again are shrunk number of
rings or hooks. also of forged steel,
and the surface of these is again turned
and polished, when the weapon is
ready for riding. This process does not
with the familiar method of growing
rilled small arms, except, of course. that
it is on a much larger scale, the gun
having been built up'-which. by the
way, is the technical name for the
above described process of jacketing
and hopping bears as striking re-
semblance to large telescope with its
joints extended, and is ready to receive
the breech mechanism; Tor it must be
borne in mind that all modern steel
cannons properly so-called are breech-
leaders. The first step in the develop
ment of the breech mechanism is known
as ''chambering This consists in en-
larging the powder chamber of the gun
to diameter several per cent. in ex-
cess of the diameter of the rifle bore, by
which device a much greater charge of
powder is enabled to be used than ever
thought of in the ordnance of the past
epoch. Roughly speaking, the power
OF a modern gun is calculated in pro-
portion as the diameter of its powder
chamber exceeds that of its rified bore,
relation being observed also to in
creased length by means of which COM
plete combustion of the entire charge is
attained.
After the chamber has been bored out
to the proper dimensions the breech
lock is fitted. This is a cylinder of
steel upon the periphery of which are
cut heavy screw threads. These
threads fit into the corresponding ones
fho IF fhn oh
rather in the prolongation of the ball
in the rear of the chamber, since this
cavity, which forms the seat of the
breech lock, is of less diameter than
the chamber itself, though somewhat
larger than the diameter of the riiled
ball. 1t is usually cut just enough
larger than the ritled ball to admit the
easy insection of the projectile which
must make a mechanical fit.
After the completion of the beech |
mechanism the gun is reacy to be |
on an experimental carriage |
for firing tests. These tests are con-
Quoted by fixed standard of, trial |
charges, which are considerable heavi-
er than those employed in service. 1t |
will be remembered that every piece of
steel used in the construction has been |
tested prior to being fitted by cutting
a piece off one end and ascertaining its |
tensile strength. ductllity and the other
qualities by actual stress in testing |
machine; in other words, subiecting it
to actual tension up to the breaking
point. so that the strength of the gun
may be calculated to nicely before
il is fired at all. The firing tests, how |
ever, are additionally necessary as a
means of determining whether the
work of putting the pieces
has been performed accurate.
w. Cincinnati Times.