IMPROVEMENTS IN RIFLING BARRELS FOR BREECH-LOADING FIRE-ARMS
Year: 1873

page_text: LETTERS PATENT to Henry Charles Marval, of Birmingham, in the
County of Warwick, for the Invention of "IMPROVEMENTS IN RIFLING
BARRELS FOR BREECH-LOADING FIRE-ARMS."-A communication from
abroad by General Hiram Berdan, of the City of New York, in the
United States of America.
Scaled the 17th June 1873, and dated the 3rd February 1873.
PROVISIONAL SPECIFICATION left by the said Henry Charles
Marval at the Office of the Commissioners of Patents, with his
Petition, on the 3rd February 1873.
I, HENRY CHARLES MARVAL, of Birmingham, in the County of
Warwick, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN RIFLING BARRELS FOR BREECH-LOADING FIRE-ARMS," being
a communication to me from abroad by General Hiram Berdan, of the
City of New York, in the United States of America, to be as
follows

page_text: any description of breech-loading guns intended to be rifled. I make
the rifling of the barrel to consist of a suitable number of broad shallow
grooves separated from each other by very narrow lands. In a transverse
section the bottom of the grooves are neither flat nor concentric with
the axis of the bore, but each is curved to a radius equal or nearly equal
to the whole diameter of the interior of the barrel measured from the
bottom of one groove to the bottom of the opposite groove and at the
centre of the width of each groove. Or the bottoms of the grooves may
be made to assume an oval form, the approximate radius of which shall
be greater than if the said grooves were concentric with the bore of the
gun. From this method of forming the grooves it will be obvious that
the internal diameter of the barrel measured at the corner of the
grooves will be larger than the internal diameter measured at the centro
of the width of the grooves, but the diameter across the corners will not
be relatively so great as it would bo if flat bottomed grooves were used.
Further, I make the lands to project towards the axis of the bore beyond
the line of the bottoms of the grooves, that is to say, the smallest
diameter of the bore at any given section is that which is measured
across from the interior face of one land to that of the opposite land.
I prefer to make the internal diameter at the centres of the grooves
equal to or nearly equal to the external diameter of the bullet, measured
outside its lubricating patch, or to the internal diameter of the mouth of
the metallic cartridge case before firing, and I make the diameter across
the corners of tho rifling almost equal to the outsido diameter of tho
mouth of the shell or the forward end of the cartridge chamber.
-
The advantages to be derived from my Invention are as follows:-
When the pressure of the gas upsets the base of the bullet the excess of
lead passes into the corners of the grooves without causing nearly so
much friction as when the grooves are concentric with the axis of the
borc, and on the other hand as compared with flat grooves the grooves
made according to my Invention have the advantage that their corners
do not out into the cartridge chamber as those of the flat grooves do
when the diameter is enlarged so as to allow the bullet to enter the
rifling without slugging or excessive friction. Morcover in a barrel
rifled according to my Invention the bullet entirely fills the grooves, and
this is very important for if the bullet do not fill the grooves it will not
be properly centered.

page_text: My improved form and depth of groove, as herein-before described,
enable the bullet to enter the barrel casily and without destruction of its
lubricating patch because the narrow lands are the only portions of the
bore which are smaller than the diameter of the bullet. When the
bullet is driven forwards it is gradually but surely centred by the
bottoms of the grooves with the least possible amount of friction in.
the operation.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry Charles Marval in the Great Scal
Patent Office on the 18th July 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
CHARLES MARVAL, of Birmingham, in the County of Warwick, send
grecting.
1
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date tho Third day of February, in the year
of our Lord One thousand eight hundred and seventy-three, in the
thirty-sixth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said Henry Charles Marval,
Her special licence that I, the said Henry Charles Marval, my
executors, administrators, and assigns, or such others as I, the said
Henry Charles Marval, 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 Ircland, the Channel Islands, and
Isle of Man, an Invention for "IMPROVEMENTS IN RIFLING BARRELS FOR
BREECH-LOADING FIRE-ARMS," being a communication to me from abroad by
General Hiram Berdan, of the City of New York, in the United States of:
America, upon the condition (amongst others) that I, the said Henry..
Charles Marval, 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 months next
and immediately after the date of the said Letters Patent.

page_text: NOW KNOW YE, that I, the said Henry Charles Marval, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by
the following statement (that is to say) :—
This Invention relates to a new or improved method of rifling the {
barrel of a breech-loading fire-arm, and can be applied to the barrel of
any description of breech-loading fire-arms intended to be rifled. I
make the rifling of the barrel to consist of a suitable number of broad
shallow grooves separated from each other by very narrow lands. In
a transverso section the bottoms of the grooves are neither flat nor
concentric with the axis of the bore, but cach is curved to a radius
equal or nearly equal to the whole diameter of the interior of the barrel
measured from the bottom of one groove to the bottom of the opposito
groove, and at the centre of the mouth of each groove. Or the bottoms
of the grooves may be made to assume an oval form, the approximate
radius of which shall be greater than if the said grooves were concentric
with the boro of the gun. From these methods of forming the grooves
it will be obvious that the internal diameter of the barrel measured
at the corners of the grooves will be larger than the internal diameter
measured at the centre of the width of the grooves, but the diameter
across the corners will not be relatively so great as it would be if
flat bottomed grooves were used. Further, I make the lands to project
towards tho axis of the bore beyond the line of the bottom of the
grooves, that is to say, that the smallest diameter of the bore at any
given section is that which is measured across from the interior of onc
land to that of the opposite land.
I prefer to make the internal diameter at the centres of the grooves
equal to or nearly equal to the external diameter of the bullet measured
outside its lubricating patch, or to the internal diameter of the mouth
of the metallic cartridge case before fircing, and I make the diameter
across the corners of the rifling almost equal to the outside diameter of
the mouth of the shell or the forward end of the cartridge chamber.
The advantages to be derived from my Invention aro as follows :—
When the pressure of the gas upsets the base of the bullet the excess of
lead passes into the corners of the grooves without causing nearly so
much friction as when the grooves are concentric with the axis of the
bore, and on the other hand as compared with flat grooves the grooves
mado according to my Invention have tho advantage that their corners

page_text: do not cut into the cartridge chamber as those of the flat grooves do
when the diameter is enlarged so as to allow the bullet to enter tho
rifling without slugging or excessive friction. Morcover, in a barrel
and
rifled according to my Invention the bullet entirely fills the grooves,
this is very important for if the bullet do not fill the grooves it will not
be properly centred.
My improved form and depth of groove, as herein-before described,
enable the bullet to enter the barrel easily and without destruction of its
lubricating patch, because the narrow lands are the only portions of the
bore which are smaller than the diameter of the bullet. When the
bullet is driven forwards it is gradually but surely centred by the
bottoms of the grooves with the least possible amount of friction in
the operation.
That my Invention may be fully understood I have annexed a
Drawing thereof which I now proceed to describe:-
The Drawing shews in transverse section, enlarged to ten times the
actual size, a barrel rifled according to my Invention. In the centre of
the Figure an outline marked A. of the rifling is shewn of the actual size
of the barrel ordinarily used. The Drawing shews six broad grooves
marked a separated from cach other by six narrow lands b, I do not
however limit myself to the number of six here shewn, as a larger or
smaller number may be used without departing from tho principle of my
said Invention. The bottoms of the grooves a are not concentric with
the bore or they would have the form shown by the dotted line c which
is or are struck from the centre d, nor are the grooves flat as shewn by
the dotted lino e. But the said bottoms of the grooves are curved to a
radius equal or nearly equal to the whole internal diameter of the barrel.
For instance the point fis the centre of the circle of which the groove
a² forms part.
I sometimes give the grooves an oval form instead of making them
portions of a true circle. In this case I make the approximate radius of
the oval used greater than the radius of the bore of the barrel and equal to
or nearly equal to the whole internal diameter of the barrel as aforesaid.
It will be seen that the internal diameter of the barrel measured at the
linc g or across the corners of the grooves is larger than the diameter
measured at the line or across the bottoms of the grooves; but that
the said diameter at 7 is not so great as it would be if flat bottomed

page_text: grooves were employed as shewn at c. Further I make cach land b to
project within a circle which would touch the bottoms of the grooves a,
as shewn by the dotted circle i, which touches the face of cach land b.
The diameter & is thus the smallest diameter of the bore at any given
transverso section. The diameter is that which I prefer to make equal
or nearly equal to the external diameter of the bullet measured outside
its lubricating patch, or to the interior of the mouth of the cartridge case
before firing, and the diameter 9 is that which I prefer to make equal to
or nearly equal to the exterior of the mouth of the cartridge caso or to
the interior of the forward end of the cartridge chamber.
Having now described the nature of my said Invention and the
manner in which the same is or may be performed, I desire it to be
understood that I claim as the Invention to be protected by the herein-
before in part recited Letters Patent, the combination of wide grooves
and narrow lands having the centres of the said grooves below the
surface of the original borc and having the bottoms of the said grooves
curved to a greater radius than if they were concentric with the bore of
thic gun substantially as herein-beforo described and illustrated in the
accompanying Drawings.
In witness whereof, I, the said Henry Charles Marval, have 2
hereunto set my hand and scal, this Thirtieth day of Junc, in
Witness,
G. R. HOLLAND,
Birmingham.
HENRY CHARLES MARVAL. (L.S.)