IMPROVEMENTS IN RIFLING FIRE-ARMS, AND IN MISSILES OR PROJECTILES USED IN SUCH, AND IN THE MACHINERY FOR THE PRODUCTION OF THESE IMPROVEMENTS
Year: 1865

page_text: LETTERS PATENT to William Ellis Metford, of Flook House, Taunton, in
the County of Somerset, andKingdomof Great Britain, forthe Invention
of "IMPROVEMENTS IN RIFLING FIRE-ARMS, AND IN MISSILES OR PROJECTILES
USED IN SUCH, AND IN THE MACHINERY FOR THE PRODUCTION OF THESE
IMPROVEMENTS."
Sealed the 23rd March 1866, and dated the 28th September 1865.
COMPLETE SPECIFICATION filed by the said William Ellis Metford at the
Office of the Commissioners of Patents, with his Petitionand Declaration,
on the 28th September 1865, pursuant to the 9th Section of the Patent
Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ELLIS METFORD, of Flook House, Taunton, in the County of Somerset, and
Kingdom of Great Britain, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS I
RIFLING FIRE-ARMS, AND IN MISSILES OR PROJECTILES USED IN SUCH AND IN THE
MACHINERY FOR THE PRODUCTION OF THESE IMPROVEMENTS," and have petitioned
Her Majesty to grant unto me, my executors, administrators, and assigns,
Her Royal Letters Patent for the same, and have made solemn Declaration
that I am the true and first Inventor thereof.
NOW KNOW YE, that I, the said William Ellis Metford, do hereby declare
that the following Complete Specification under my hand and seal, fully

page_text: describes and ascertains the nature of the said Invention, and in what
manner the same is to be performed, in and by the following statement:-
My Invention relates to an improved spiral or rifle curve in the inside of
the barrel of rifles, muskets, or cannon, and also in the construction, form,
and compound of explosive and other missiles, bullets, or projectiles used
in such arms, and in the machinery used to effect these objects herein set
forth,
CHAPTER 1.
The first part of my Invention relates to an improved spriral or twist in the
barrels of rifles, muskets, or cannon of such a character as shall impart to the
bullet its spiral rate of rotation under some definite law of developement for
the torsional force. The present system of cutting the twist in barrels would
only be correct if the propelling force of the powder was uniform throughout
the length of the barrel, for then only would the torsional force applied to
the bullet be uniform throughout, (that is,) the growth of the linear velocity
of the bullet would take place exactly on the same law on which a falling
body moves, it will then be found that the torsional movement will at every
point be exactly proportional to its linear movement. The propelling force
of gunpowder is such that the decrease of pressure towards the muzzle is
governed by the law that the elastic force of vapour varies inversely as the
space it occupies. In the usual system of twist the spiral as developed on a
flat surface becomes a straight line, and in cases where the correct principles
have been roughly guessed at, the proper developement of the curve has not
been attempted, so that little attention has been paid to the true principles of
th curve so as to meet the conditions required by the graduated force that
impels the bullet. In my improved construction I propose a spiral of such a
character that the rotation shall be given under the most economical conditions,
that is, this curve shall be such that the bullet shall receive equal increments
of rotation in equal times, beginning this rotation at its starting, and er.ding
it at or near the muzzle of the piece; therefore the intention of "stripping"
being equal only to the amount due to the pitch cf the starting slope, which
will be reduced to a minimum, as also the friction. I do not, however, con-
fine myself to this position, as I may wish to impart to the bullet either
increasing or decreasing increments of rotation in equal time, the amount
being governed by a definite mathematical law of increase or decrease. If
the spiral be developed on a flat surface as before described, and the pressure
of the bullet against the grooved edge be taken into account, it will be com-
pressed thus: That if a tangent be drawn to the curve at any point P, andwe
speak of the angle of twist as the angle included between the tangent and the

page_text: axis.,,then the angle of twist must be such that the
product of its secant and its tangent shall always be in
inverse proportion to the pressure of the gas at that
instant, which will be fully understood by the following
formula and diagram,
P =
n
=======
required constant pressure,
some constant multiplier depending on the
starting value of P.
flocal force of powder.
0
=
angle which gives the result.
n P
The we obtain
tan
sec 0.
This curve having been obtained, and in order that
the rifling machine should be supplied with a guide bar
capable of describing this curve, and also that the
same guide bar night be altered to suit these implied
conditions for all barrels of whatever length or calibre,
I have invented what I term my improved guide bar,
as shewn in Diagram Fig. 1, Sheet 2, which represents
a plan half full size of the guide bar as affixed to
the bed of the rifling machine, the bed being described
by the line,, On this bed are affixed the two studs
or brackets L and L. Through the bracket L is the
radius pin o, on which the one end of the bar A
radiates, and through the bracket L'. is the pin P', on
which the regulating bar radiates also, which is divided
so as to regulate and register the angle of the rifle bar
at any position, which is altered by means of the set
screw Q, sliding in the slot R. If it be necessary to
alter the curve on the bar A, B, and D, in Figs. 1,
3, and 4, so that any new curve may be established for
any specialty, the nuts of the bolts Ẹ and the screws G
are slackened, and the steel straight-edges are thus
capable of being bent to suit the new adjustment, for
by the aid of the divisions on the brackets B, shewn
in Fig. 4, the position of the steel straight-edges at
each point B1, B₁, may be set to the greatest nicety,
and the desired curve obtained from these adjustments
at such ordinates.

page_text: In order to render the construction of this adjustable rifle bar more
intelligible, I will describe the parts separately.
A, cast-iron planed curved bar; B, brackets for holding together the bar
and the steel straight-edges which are divided for registering position; C, a
saddle piece which fits over the steel strips or "straight-edges D, which are
made parallel and pefectly true, and are about one-eighth to one-tenth of an
inch thick. The saddle piece C, which fits over the steel strips, see Fig. 3, is
attached by a bolt E, fitting into the bolt hole (shewn in Figs. 2 and 3), to
the rack which moves the rifling pinion, the arrangements of which are so
common to rifling machines that it is not shewn, but I may mention it is
precisely the same as in the machines generally in use in this respect. E, the
bolts attaching the bar A and brackets B together; F, packing pieces for
the screws G to bind against. H, H, are hardened and tempered steel
bearing pieces; these take the friction off the saddle C when the cut is being
made on the barrel, and are able to rock on the screws I, thus they easily
adjust themselves to the altering curve. K, a spring of steel to keep the
pieces H against the straight-edges on the machine moving forward for the
next cut; L and L', brackets for attaching the bar A to the rifling machine
and cross bar M, divided in lines for registering the position' of the rifle bar.
O, the radius pin for the bar to radiate on, and P, the radius pin for the cross
bar M Q, the set bolt; R, the slot for Q to play through when regulating
the extreme of the curve, which is determined by the divisions on the bar M,
while the intermediate distances are regulated by the divisions on each
bracket B, as in Fig. 4, shewn full size. This adjunct of registering rifle
bars attached to a rifling machine, so that a curve of any character may be
obtained by the various adjustments herein described, constitute another part
of my Invention for obtaining perfection in the manufacture of rifle fire-
arms, and also the cutting of grooves in rifle barrels of the character and
curve as described in the annexed formula, which constitute another part of
myInvention, as it enables the operator to reconstruct any curve when once
such curve has been set off on the bar from diagram projected on paper,
which is done by placing the bar on the drawing and adjusting it to agree,
the several adjusting points as before described being sufficient to obtain
curves for any sized barrels.
CHAPTER 3.
Another part of my Invention is in the construction of hollow explosive
shells to be fired from such rifles as before described, and in the explosive
compounds used for such, and also in the peculiar character of the machinery

page_text: to effect these purposes. I would here remark that the bullets of the form
herein described, and shewn in Figs. 4, 5, and 6, and also in Figs. 1, 2, and
3, Sheet 1, when filled with their explosive compound, when entering any body
or even fluid, froin their great inital velocity of at least 500 feet per second,
that while the ball or shell punches a hole equal to its own diameter on entering
any material,at the same time the cavity formed for the explosive compound
cuts a plug equal to its diameter also, which plug enters the cavity as above
named, fires the explosive compound by compression, creating great destruc-
tion; it also explodes in the same manner on entering water and other fluids
These explosive shells are composed of metal of any kind, but for the smaller
shells I prefer lead, or any alloy of which lead is the chief ingredient, the
form of which will be readily seen in section Figs. 1, 2, and 3, Sheet 1.
The lower cavity a of these shells, when such is required, may be provided
with a plug of wood in the ordinary way,or with any other light substance;
the upper part of the shell has also a hollow cavity b, but of such a depth
and capacity that the position of the partition of metal (which is left in the
centre) is that when the shell is filled it brings its centre of gravity in the
right place,so that the shell in its range shall not be disturbed from influences
resulting from mal-construction. This form of shell was invented and used
by me as a simple non-explosive missile in the year 1861, and subsequently
patented by Joseph Whitworth, of Manchester. But I now place in the
upper cavity of this shell an explosive compound composed of, by weight, 1 to 1,
2 to 1, 3 to 1, or 4 to 1 of chlorate of potash and sulphur, or even a greater
proportion, if the arrangements of the bullet demand it. This composition I
usually mix in a sieve after being brought to a state of fine powder, the fineness
being governed by the amount of tenderness ofexplosion which I desire to give
to the bullet,and I mayhere state that I do not prefer the bullet to be too explo-
sive; my usual test is that the bullet travelling at 1100 feet per second should
explode in about three-eighths of an inch of soft deal; and not in one-quarter of
an inch; again,if I require to increase the percussion qualities, I grind the mix-
ture together damp, with or without a verysmall quantity of adhesive substance
and granulate it, but I can attain the same end by having a shorter and larger
hollow in front of the bullet. I do not bind myself, however, to use entirely
chlorate of potash and sulphur, but I object to the preparations of silver and
mercury,as being unnecessary and very dangerous. I do not confine myself
to a plain hollow of lead or lead alloy, as I may prefer lining this hollow with
metal of greater tenacity; but shells for small arms usually require no
such lining. I also construct my shells when there is room, with an additional
cavity cat the bottom of the greater cavity b, as shewu in Diagram Fig. 4 in

page_text: Sheet 1, which I fill with any mixture which will burn like a port-fire. This
shell is especially designed to make more sure of powder destruction in maga-
zines, as it may happen that the bullet may have to pass through two parti-
tions with some space between them, although in such a case the simple form
has been proved to be very successful; such an addition will ensure even
greater certainty,as the back of the bullet, which bears the little squib, will
pass well into the powder and there burn.
A third form is also shewn in Fig. 5, Sheet 1, a being the usual chamber
as before; b, the upper chamber as before; d, a brass ball similar to
common globular metal button; in this case may be a shorter tube. The
bottoms of these hollows a in these shells are corrugated. These shells are
filled thus-Fine gunpowder is introduced into the hollow ball, which is
filled well up, as is also the chamber b; a little meal powder is then placed
in chamber 6; then a metal disc is dropped down (this disc is not a very
tight fit) on to the mealed powder, on which it is driven tight; then the usual
percussive charge is put into the chamber 6. The action of the shell is thus:
-On striking the material, forming as it does the column of resistance, of
which the wax pellet or any other plastic and adhesive composition is merely
the head (and which may be away altogether, except that it secures the
explosive mixture from wet and premature lighting from the fire of the rifle),
it explodes the compound in the chamber b, and were it not for the metal
disc it would also light the gunpowder; and when an exceedingly quick
second explosion is required the disc may be omitted. This disc blocks the
fire of the first charge, but does not prevent the meal powder from setting
fire and burning to the gunpowder in the chamber d. Thus the second
charge is lighted a moment later than the charge b. The corrugation at the
bottom of the chamber is merely to give a surer ignition. This shell is
perhaps too exceptional for general war, but it is designed with an especial
view to destroy very heavy game, such as tigers and other obnoxious beasts.
I also construct bullets or shells as in Fig. 6, making the head of a
spiral form, having wings or spiral grooves cut thereon, for the purpose of
maintaining and if necessary increasing its rotary motion already given by
the curve in the barrel by the action of such spiral-formed head on the air in
its course to the target, this only being necessary in very long ranges, thereby
aiding in maintaining centrilization in its flight.

page_text: of the machine; Fig. 2, a cross section through N and O, shewing the shells
and the punches forcing down the composition; Fig. 3 is also the same
cross section through N and O, but shewing the punches e, e, e, for cover-
ing each aperture with the wax pellets f, f. A, the base of the machine,
which is fixed to any convenient wood bench; B2, B3, studs, on which
radiate four frames C, C, C1, C1, C2, C; D, D, are gun metal platforms; the
right-hand one is pierced with ten holes, g, g, countersunk on their lower
sides, and of the shape or form of the top of the shells or bullets to be
operated on. This platform is of such a thickness, that on the shell being
filled with one filling (that is with the explosive compound) there should be
just room enough for the wax pellets or stoppers f. f. The left-hand platform
C has 10 holes, and is also counter-sunk on its lower side. This platform
has asteel bridge h, which is also perforated with ten holes, and through which
the punches E, E, E, pass. Under this bridge is placed a wax slabi, which
has been previously heated to 108°, and papered on one side with any colored
or white paper, out of which pellets are punched, and the jerk which cuts
out or punches these pellets also forces the said pellets home in the front
cavity b of the shell; these punches have concave surfaces, and thus the
wax pellets, on being punched and driven "home," take a curved shape on
their outside surfaces, and by this means the shape of the bullet is retained.
C² and C² are two working frames, each carrying ten punches of steel marked
E, E, E, E; the right-hand punches are for stamping or forcing the explosive
composition into the cavities 6 of the shells; the left-hand frame is for
cutting out and punching into the heads of the shells the wax pellets f,f.f.f.
D, Fig. 1, is a lever which enables the operator to withdraw the punches
e, through the wax i, i, in which they would otherwise stick. M' is a
metal box in which the shells are placed and confined correctly under the
punches E. F, an india-rubber band acting as a spring or flexible medium to
keep the levers Dand G together and yet give them a necessary play when
in operation so as to bring the punches out of the wax without tearing it; this,
with the assistance of the curved heels to the levers marked H, H, working
against "pellet pieces" or curved surfaces I, I, releases the punches from the
wax, which is caught on the steel bridge plate h, h. J and J' are steel rods,
against which the frames C2, C2, are thrown. K, K' are two steel springs
attached to the bed A of the machine, which fixes the frames C and C1, and
prevents accidental lifting while in operation. L, a zinc trough in which the
explosive compound is placed.
The action of the machine is, that the zinc trough having been filled with
dry composition as per formula, and ten or any number of bullets having been

page_text: placed in the cells M', M', the frame or platform C" on the right-hand side is
brought down on the bullets or shells and held there by the two spring catches
K and K. The trough is then emptied over the row of holes which are in
the swinging frame C¹, the powder falls into the shells to the level of the
holes sg; the superfluous powder is swept back into the zinc trough (which
has already boen placed in its position) with a wood knife; the hand of
the operator then seizes the knob of the right-hand frame carrying the
punches E, E, and swings the frame C2 down on the composition. This frame
is then swung back on the steel rod J¹; the platform C¹ is released from the
spring catches K, K', and thrown back on the frame C2. This is the first part
of the operation.
The platform (left hand) is brought down and locked by the spring
catches K and K. The sheet of wax i, covered with paper on the upper
surface, and kept at a temperature of about 108° Fahrenheit, is pushed under
the steel bridge h, h. The operator's hand then takes the lever D, and with a
sharp action brings down the frame C2 (left hand) rapidly on the wax i, i,
At this instant the right hand strikes the head of the lever with an horizontal
motion, and thus lifts the punches E, E, E, (left hand) out of the sheet of
wax, the steel plate preventing the wax from rising with the punches;
the same motion of the hand also projects the whole frame (left hand) back
on the steel rod J; the bullets or shells are then released from the cells and
taken to a "cupped" punching machine, which slightly turns over the edge of
the metal around the wax plugs f, preventing the wax and explosive com-
pound from damp, and making it perfectly secure and water-tight.
I do not confine myself to this method of driving in the composition, as also
the method of filling by the swinging frames as herein-before described, as the
machine may be made so as to move the punches between vertical slides, and
may be actuated on by cams, cranks, screws, or levers; the frames having
the holes sliding over the bullets and being lowered on them preparatory to
filling and stopping. The small cupped punching machine and copper punch
for closing the head of the bullet need no description.
The wax sheets, from which the "pellets" are punched, are made thus:—A
damped sheet of paper is laid on a metal slab, round the sides of which are
loose metal walls. The walls are then so placed round the edge of the square
metal slab that the paper is caught between the lower surfaces of the walls
and the slab, in which position they are secured with screws; the slab is then
heated the paper dries and gets tight. The slab is then levelled with a

page_text: circular spirit level, and a proper weight of melted wax at 190° Fahrenheit
is poured on the paper; as it sets the screws holding the walls are withdrawn,
and it is released and kept ready for use. When iu use, the sheet of wax is
kept in a little hot water oven, which has an opening in its side, from which
it can be easily extracted when the sheet is to be laid under the punches.
These shells explode on entering any body or substance having a certain
thickness, rendering it a most destructive missile.
Having thus described the nature of my said Invention in the perfection-
ment of rifles, and missiles or projectiles used in such arms, and also in the
machinery for producing the several parts of my Invention, I desire it to be
distinctly understood that I do not confine myself to the exact details as herein
shewn and specified, as long as the inain elements of my improvements in arms
and their projectiles, and in the machinery for effecting such objects, are
adhered to. What I claim as my Iuvention is,
First, the construction of rifle barrelswithcurvosof thecharacterasdescribed
and laid down in the annexed formula, and in the machinery for producing
such curves, as fully set forth in Chapters 1 and 2, and shewn in the annexed
Drawings.
Second, the form of explosive missiles or projectiles filled or unfilled, and
the explosive composition used in such, and the machinery for effecting the
objects, herein-described in Chapters 3 and 4.
Third, the forming the head of such explosive bullets ormissiles spirally for
the purpose of maintaining the rotary motion already imparted to it by its
action against the atmosphere in its course at long ranges towards the target
as fully set forth in Chapter 3.
In witness whereof, I, the said William Ellis Metford, have hereunto
set my hand and seal, this Fifteenth day of July, in the year of our
Lord One thousand eight hundred and sixty-five.
W. E. METFORD. (L.S.)