IMPROVEMENTS IN PROJECTILES FOR RIFLED ORDNANCE, AND THE METHOD OF MANUFACTURING THEM
Year: 1864

page_text: PROVISIONAL SPECIFICATION left by Bashley Britten at the Office of
the Commissioners of Patents, with his Petition, on the 26th July
1864.
I, BASHLEY BRITTEN, of North Vale Lodge, Red Hill, in the County of
Surrey, Gentleman, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN PROJECTILES FOR RIFLED ORDNANCE, AND THE METHOD OF
MANUFACTURING THEM," to be as follows:-
My object is to manufacture projectiles suitable for rifled guns by a method
which shall obviate the necessity of the projectiles being turned or planed by
machinery, which projectiles shall be of very easy construction, and also of
such a nature as to combine many of the chief advantages which severally
appertain to the various systems of projectiles which have hitherto been chiefly
used for rifled guns.
The rifling for which these projectiles are best adapted consists of several
shallow helical grooves in the bore of the gun, and I make corresponding
projecting ribs on the projectiles. The sides of the grooves I have inclined at
a very considerable angle to the radius of the bore, or sloping from the surface
of the bore in such a manner that during the passage of the projectile either
down the gun from the muzzle in loading or towards the muzzle when dis-
charged, the sloping sides of the grooves tend to centre the projectile in the
bore, or to bring the axis of the projectile coincident with the axis of
the bore.
I make the body of the projectiles of cast iron, wrought iron, or steel, of a
more or less cylindrical shape, with the front hemispherical, conoidal, or any

page_text: other convenient form, the projecting ribs being formed by the moulds or
dies used for casting, forging, or pressing the iron or steel into the required
form.
The iron or steel portion of the projectile I make of such dimensions as to
allow of a partial coating of pewter, alloy, or other moderately yielding metal
to be cast over and attached to it. For putting on this coating of yielding
metal I employ moulds which have rifled grooves in them corresponding as
nearly as possible with the rifled grooves of the gun. The inside of these
moulds is so finished that they shall produce the necessary accuracy on the
surface of the projectiles without its being required to turn or plane them by
machinery. The moulds are made in two or more segments, held together by
external rings or other convenient means which will allow of the moulds being
readily detached from the projectiles. The moulds are made of such dimensions
that the projectiles formed in them may go easily into the gun.
The form of the iron or steel body of the projectiles and the form of the
interior of the moulds are so made that the coating of yielding metal shall be
for the most part as thin as it can be produced; but round the outer edge of
the base of the projectiles, placed next to the cartridge, I make the yielding
metal thick enough to allow of its being set up and bulged by the force of the
explosion of the charge, so as to more completely fill the bore and prevent
escape of gas; and I also have an increased thickness of the yielding metal on
those sides of the projections which bear against the sloping sides of the rifle
grooves in the gun when the projectiles are discharged, in order that the rifling
in the gun may not be seriously injured by contact with the hard metal.
For attaching the coating of pewter, alloy, or other yielding metal to the
iron or steel body of the projectiles I adopt a plan already known, and described
by me in the Specification of a Patent dated 1st of August 1855, No. 1740.
The process is as follows:-The iron or steel surfaces of the projectiles having
been cleansed by acid or other means are first coated with zinc or tin in the
usual method termed galvanizing or tinning iron. While this coating of zinc
or tin is in a fuzed state on the projectiles they are placed in the finishing
inoulds with the melted pewter or yielding metal to be attached to the pro-
jectiles. When the yielding metal has set the projectiles are removed from
the moulds and allowed to cool.