IMPROVEMENTS IN RIFLED SMALL ARMS AND ORDNANCE, IN TOOLS OR APPARATUS FOR RIFLING THE SAME, AND IN PROJECTILES FOR THE SAID ORDNANCE
Year: 1870

page_text: LETTERS PATENT to William Hastings Sim, of the Royal Military
College, Sandhurst, in the County of Hants, Gentleman, for the
Invention of "IMPROVEMENTS IN RIFLED SMALL ARMS AND ORDNANCE,
IN TOOLS OR APPARATUS FOR RIFLING THE SAME, AND IN PROJECTILES FOR
THE SAID ORDNANCE."
Sealed the 14th February 1871, and dated the 18th August 1870.
PROVISIONAL SPECIFICATION left by the said William Hastings Sim
at the Office of the Commissioners of Patents, with his Petition,
on the 18th August 1870.
I, WILLIAM HASTINGS SIM, of the Royal Military College, Sand-
hurst, in the County of Hants, Gentleman, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN RIFLED SMALL ARMS AND
ORDNANCE, IN TOOLS OR APPARATUS FOR RIFLING THE SAME, AND IN PROJECTILES
FOR THE SAID ORDNANCE," to be as follows:-
My Invention relates, firstly, to the rifling or grooving of the barrels
of small arms and ordnance in general, but is especially applicable to
barrels in which what is termed "a gaining twist" is used, that is to

page_text: say, barrels the grooves or spirals in which decease in pitch towards
the muzzle in order to impart to the projectile a progressively increasing
rapidity of motion around its axis as the said projectile approaches the
muzzle.
Rifled barrels of the ordinary sections, especially where the grooves
have a 66
gaining twist" as above described, have a tendency to cause
the lead of the projectile to strip or (where an iron projectile is used) to
damage those parts of the projectile which enters the grooves.
Now in order to obviate these defects I make in the barrel of the
gun grooves having the transverse sectional form represented in the
are curved at a, a, and flat at b, b, the curves a, a, being of the same
or nearly the same radius as the inner circumference of the barrel,
which latter is indicated by the dotted circle. The said curves are
struck excentrically and spring from the said inner circumference of
the barrel and terminate at the parts where the grooves are of greatest
depth, such parts being connected to the parts where the next curve
begins by the flat radial sides b, b. Although in the diagram I have
indicated three grooves I do not limit myself to that number.
I prefer to make the " gaining twist” herein-before referred to in
the following manner :-I take a cylindrical bar of steel of about double
the length of the barrel to be grooved. At the middle of this bar
I form projections with cutting edges of the shape necessary for
cutting grooves of the required sectional form. I then take two sheets
of paper, each of which is equal in length to that part of the barrel
which is to be rifled, and equal in width to the circumference of the
aforesaid bar, and on each sheet I strike a series of curves from centres
on a line at right angles to the greatest length of the paper, such iine
being drawn from one end of each sheet, the said curves being of such
radius that when each sheet is rolled around the bar as hercin-after
described the said curves shall make three-fourths of a turn (or there-
abouts) around the said bar. Having thus set out the curves I roll
the said sheets of paper around the bar one sheet at each side of the

page_text: cutting tool formed on the said bar, and I then by means of suitable
instruments cut around the said bar guide grooves of the pitch shown on
the paper.
The grooved bar thus formed works through stationary
screw boxes or collars furnished with projecting threads which engage
in the guide grooves in the said bar, so that the said bar as it is forced
through the barrel receives the axial motion requisite for the formation
in the said barrel of grooves with a “gaining twist."
My Invention consists further of the improved projectile to be used
with ordnance having rifle grooves of the sectional form herein-before
described. I make the said projectile of iron, which I cast of a cylindro-
conoidal form with projections around its circumference of a form
corresponding to the sectional form of the grooves in which the said
projections are to engage, and I coat the said projectile with lead or any
suitable soft metal or alloy. At the rear of the projectile I form or fix
a pin or axis on which I mount a wooden sabot or shield which acts as
a gas check.
The form of the said sabot corresponds in transverse
section with the sectional form of the grooves in the barrel. The said
sabot is capable of independent rotation on the pin or axis aforesaid,
and serves to keep the axis of the projectile parallel with that of the
barrel and also prevents escape of gas. After the projectile has left the
gun the sabot falls from the pin and leaves the said projectile unimpeded
in its flight.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Hastings Sim in the Great Seal Patent
Office on the 17th February 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
HASTINGS SIM, of the Royal Military College, Sandhurst, in the
County of Hants, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of August, in the year
of our Lord One thousand eight hundred and seventy, in the thirty-
fourth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said William Hastings Sim, Her special licence
that I, the said William Hastings Sim, my executors, administrators,

page_text: and assigns, or such others as I, the said William Hastings Sim, my
executors, administrators, and assigns, should at any time agree with,
and no others, from time to time and at all times thereafter during the
term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
RIPLED SMALL ARMS AND ORDNANCE, IN TOOLS OR APPARATUS FOR RIFLING THE
SAME, AND IN PROJECTILES FOR THE SAID ORDNANCE," upon the condition
(amongst others) that I, the said William Hastings Sim, my executors
or administrators, by an instrument in writing under my, or their, or
one of their hands and seals, should particularly describe and ascertain
the nature of the said Invention, and in what manner the same was
to be performed, and cause the same to be filed in the Great Seal
Patent Office within six calendar month's next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said William Hastings Sim, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement thereof, that is to say:
65
-
My Invention relates, firstly, to the rifling or grooving of the barrels of
small arms and ordnance in general, but is especially applicable to barrels
in which what is termed a gaining twist" is used, that is to say,
barrels the grooves or spirals in which decrease in pitch towards the
muzzle in order to impart to the projectile a progressively increasing
rapidity of motion around its axis as the said projectile approaches the
muzzle.
r
Rifled barrels of the ordinary transverse sections, especially where the
grooves have a
'gaining twist" as above described have a tendency to
cause the lead of the projectile to strip or (where an iron projectile is
used) to damage those parts of the projectile which enter the grooves.
Now in order to obviate these defects, I make in the barrel of the gun
grooves having the transverse sectional form represented in Figures 1 and
2 of the accompanying Drawing, that is to say, the said grooves are
curved at b, b, and flat at b¹, 6¹, the curves at b, b, being (where three or
four grooves are used) of the same or nearly the same radius as the inner
circumference or bore of the barrel, which latter is indicated by the
dotted circle. The said curves are struck excentrically and spring from

page_text: the said inner circumference of the barrel, and terminate preferably at
the parts where the grooves are of greatest depth, such parts being
connected to the parts where the next curve begins by the flat radial
sides b¹, b¹.
'
I prefer to cut the grooves in the gun by means of tools made as
follows
-I take a cylindrical bar of steel of about two and a half times
the length of the barrel to be grooved. At the middle of this bar I form
projections with cutting edges of the shape necessary for cutting grooves
of the improved sectional form herein-before described. Around the said
bar I form guide grooves of a pitch corresponding to that of the grooves
to be cut. The bar works in stationary screw boxes, the projecting
threads of which engage in the grooves in the bar, so that the said bar
as it is forced through the barrel receives the axial motion necessary for
the formation of the "twist." A series of these tools may be used, the
cutters of each succeeding tool being larger than those of the preceding
tool.
My Invention consists further of an improved projectile to be used
with ordnance having rifle grooves of the sectional form herein-before
described. I make the said projectile of iron which I cast of a cylindro-
conoidal form-with projections around its circumference, such projections
being of a form corresponding to the sectional form of the grooves in
which the said projections are to engage, and I coat the said projectile
with lead or any suitable soft metal or alloy. Instead of casting the
projections on the projectile, copper studs may be inserted therein, so as
to constitute projections which engage in the deepest part of the grooves
of the gun. At the rear of the projectile I form or fix a pin or axis on
which I mount a wooden sabot or shield which acts as a gas check. The
form of the said sabot corresponds in transverse section with the sectional
form of the grooves in the barrel. The said sabot is capable of inde-
pendent rotation on the pin or axis aforesaid, and serves to keep the axis
of the projectile parallel with that of the barrel, and also prevents escape
gas. After the projectile has left the gun the sabot falls from the pin
and leaves the said projectile unimpeded in its flight.
of
P
Having now described the nature of my Invention I will proceed to
describe the manner in which the same is to be performed, reference
being had to the accompany Drawing, and to the letters and figures
marked thereon. -

page_text: Figures 1 and 2 are transverse sections of guns having grooves of the
form constituting this part of my Invention, the gun Figure 1 having
three grooves and the gun Figure 2, four grooves. Figure 3 is a diagram
showing one way in which I set out the grooves.
a (see Figures 1 and 2) is the barrel of the gun, and b, b, are the
grooves. In setting out the said grooves I strike a circle c (see Figure 3)
equal to the bore of the gun and divide the said circle into as many
equal parts as there are to be grooves, and I draw radial lines d, d, from
the centre of the said circle through the points of division thus laid off,
and lay off from d¹ to d² on cach line a distance equal (preferably) to the
greatest deptli of each groove. I then strike a series of curves e, e, from
the outer point d² of each radial line to that part of the circle intersected
by the next radial line. The curves e, e, and the short radial lines d³, d³,
thus set out represent the transverse sectional form of the grooves. The
radius of the curves will depend upon the number of the grooves.. Where
three only are employed the radius which I prefer is slightly greater
than that of the original bore of the barrel. Where four grooves are
employed I prefer to make the radius of the curves equal to that of the
said bore. Where more than four grooves are employed the radius of
the curves will be proportionately smaller.
I prefer to make the grooves deepest at their flat sides as illustrated
in Figures 1, 2, and 3. The said grooves may, however, have their
greatest depth at points intermediate to their flat sides, as represented in
the diagram Figure 4. In setting out the grooves according to this
modification I divide the circle ƒ as before into as many equal parts as
there are to be grooves, but instead of striking the curves from radial
lines drawn from the points of division g, g, thus set out I draw radial
lines h, h, through the circle at the points where the grooves are to be
deepest, and lay off on these lines from h¹ to h³, distances equal to
the greatest depth of the said grooves, and then from centres on the
said lines strike curves i, i, of such radius that they starting from
the points g, g, shall intersect the points h², h². I then draw short
radial lines j, j, from the points g, g, intersecting the curves. The
curves i, i, and radial lines j, j, thus set out represent the transverse
sectional form of the grooves. The angle g, l, k, should not be greater
than two-fifths of the angle g, k, g, in order that the outer ends of the
curves i, i, may be at a sufficient distance from the circle f to leave the

page_text: flat radial sides j, j, of sufficient depth. I prefer to make the twist of
the grooves from right to left, i.e., in the opposite direction to that of
the "Enfield " twist.
Figures 5 and 6 represent in side elevation and transverse vertical
section respectively the middle portion of one of a series of tools which
may be employed for cutting the grooves herein-before described.
The tool consists of a cylindrical bar of steel m about two and a half
times the length of the barrel and of such diameter as to slide therein
easily but without vibration. At the middle of this bar are formed
cutting edges n, n, equal in number to the number of grooves to be cut.
In the first tool of the series the cutting edges are of small size, so as to
cut shallow grooves which are subsequently deepened by successive
tools, each of which has larger cutting edges than the preceding tool,
the cutters on the last tool being of the exact size of the grooves to be
cut. The bar m is turned down at o to a depth of about twice the depth
of the grooves in order to afford space for the metal cut out of the gun
as the tool passes through it in the direction indicated by the arrow.
The edges n, n, are curved to a pitch corresponding to that of the
grooves to be cut, and guide grooves p, p, of the same pitch are cut
around the bar m which works through stationary screw boxes so that
as the said bar is driven forward it is caused to revolve as required.
I do not consider it necessary to describe any way of forming the
guide grooves p, p, (whether they are of a pitch equal throughout or
have a gaining twist") because the formation of such grooves is well
5 known and constitutes no part of my Invention; neither do I limit
myself to or claim the cutting tools or apparatus herein-before described
as the grooves of the gun may be cut by means of any other suitable
tools or apparatus.
Figures 7 and 8 represent in side and end elevations respectively a
O projectile made according to my Invention to be used with guns having
the improved sectional form of grooves herein-before described; q is the
projectile and (see Figure 8) is the coating of lead or soft alloy thereon.
On the fore part of the projectile are cast projections s, s, the form of
which corresponds with the sectional form of the grooves in which the
5 said projections are to engage; t is a slightly conical pin which is cast
on or fixed in the base of the projectile and carries the wooden sabot u
which is of a sectional form corresponding to that of the barrel of the

page_text: gun.
The said sabot is capable of independent rotation and serves to
keep the axis of the projectile parallel with that of the barrel and also
prevents the escape of gas. After the projectile has left the gun the
sabot u falls from the pint and leaves the projectile unimpeded in its
flight. Instead of mounting the sabot on a pin fixed in the base of
the projectile the said pin may be fixed in or upon the sabot and turn
in a hole in the base of the projectile.
elevations respectively a
According to this modi-
projections herein-before
Figures 9 and 10 represent in side and end
modification of the projectile above described.
fication copper studs v, v, are substituted for the
referred to. I prefer to fix these studs in the projectile by screwing
them therein. They project sufficiently to fit the deepest part of the
grooves in the barrel of the gun. The sabot (not shown in these Figures)
is of the same shape as the sabot u, Figures 7 and 8, and fits on the
pin w. x is the coating of lead or soft alloy..
The projectiles herein-before described may be used with rifled
ordnance in general (the projections on such projectiles having the
sectional form of the grooves in which the said projections are to engage),
but are especially applicable to guns rifled with a "gaining twist," as,
owing to the sabot being capable of independent rotation, its projections
do not jam in or strain the grooves, as would be the case if the said
projections were formed on the rear part of the projectile itself.
Having now described the nature of my Invention, and the manner
in which the same is to be performed, I claim as my said Invention,-
Firstly. The improved mode of rifling herein-before described and
illustrated in Figures 1, 2, 3, and 4 of the accompanying Drawing, that
is to say, making in the barrels of small arms and ordnance grooves the
curves of which spring from that which was previously to rifling the
plain bore of the barrel, and terminate at flat radial sides-which connect
the end of one curve with the beginning of the next.
Secondly. The improved ordnance projectiles herein-before described
and illustrated in Figures 7; 8, 9, and 10 of the accompanying Drawing,
that is to say, projectiles furnished at their fore parts with projections or
studs of forms suitable for engaging in the grooves of the guns with
which such projectiles are to be used, wooden sabots of suitable sectional

page_text: form and capable of independent rotation being mounted at the rear
ends of the said projectiles, aș and for the purposes described.
In witness whereof, I, the said William Hastings Sim, have here-
unto set my hand and seal, this Sixteenth day of February, in the
year of our Lord One thousand eight hundred and seventy-one.
Witness,
H. H. MURDOCH,
7, Staple Inn,
'W.C.
W. H. SIM.
(L.S.)