IMPROVEMENTS IN ORDNANCE, AND IN TOOLS FOR RIFLING THE SAME, PARTS OF WHICH IM- PROVISIONAL SPECIFICATIONLICA
Year: 1862

page_text: LETTERS PATENT to Perceval Moses Parsons, of Blackheath, in the
County of Kent, Civil Engineer, for the Invention of "IMPROVEMENTS
IN ORDNANCE, AND IN TOOLS FOR RIFLING THE SAME, PARTS OF WHICH IM-
PROVISIONAL SPECIFICATION left by the said Perceval Moses Parsons
at the Office of the Commissioners of Patents, with his Petition, on
the 5th June 1862.
I, PERCEVAL MOSES PARSONS, of Blackheath, in the County of Kent,
Civil Engineer, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN ORDNANCE, AND IN TOOLS FOR RIFLING THE SAME, PARTS OF
WHICH IMPROVEMENTS ARE APPLICABLE TO SMALL ARMS," to be as follows:-
My Invention consists, firstly, of certain methods of constructing ordnance,
the object of which is to enable guns to be made of larger calibre and greater
strength than can be obtained by the methods of construction now in use.
For this purpose I employ a tube, made by preference of wrought-iron, steel,
or homogeneous metal, which forms the bore of the piece; this is turned on
the outside, and has a screw thread of suitable form cut upon so much of its
length as is necessary, and upon this tube another tube, or a series of tubes or
rings of wrought-iron, steel, or homogeneous metal, having a corresponding

page_text: screw thread cut on its or their interior, is or are screwed, so as to encase the
inner tube, either the whole or a portion of its length, as may be necessary;
should additional thickness be required, a screw thread is then in like manner
cut on such portion of the length of the exterior of the last tube, or series of
tubes or rings, and another tube or series of tubes or rings is or are screwed
on, and this process is repeated until the requisite thickness is obtained. The
tubes should be so put together that the outer rings or tubes will be in a state
of tension, and the inner rings or tubes in a state of compression, and this
may be effected either by making the outer rings the requisite amount smaller
than the inner rings, and expanding the outer tubes or rings by heat, then
screwing them on, and allowing them to contract on the inner tube or rings
by cooling, or by making the tube and rings slightly conical, and adjusting
their sizes so that by screwing the rings on to their intended position the
requisite force will be applied to produce the desired initial strain. For the
purpose of giving greater strength to guns which are composed mainly of cast
iron, I bore out a recess, by preference of a conical form, at the breech end of
the gun, larger in diameter than the intended finished size of the bore, but
extending only a portion of its length, and I fit into the recess a tube of
wrought-iron, steel, homogeneous metal; or other suitable material accurately
turned to the shape and size of the recess, and secure it by a breech plug screwed
into the breech of the gun in the case of muzzle-lóading guns, or by a nut or
hollow screw in the case of breech-loaders. The tube may be in one piece of
metal or built up of several, either by fitting two or more rings together, or by
shrinking, forcing, or screwing one or more tubes or rings on to an inner tube
or tubes; in some cases I apply a tube of this description in combination with
a tube of wrought iron, steel, homogeneous metal, or other similar material,
with which the gun is lined throughout the whole length of the bore.
My Invention secondly consists of a peculiar form of rifling, which is
applicable to small arms as well as to ordnance, although it is particularly
suited to ordnance, as it enables hard metal projectiles to be used, which do
not require to be machine-shaped or made with greater accuracy than can
ordinarily be obtained by casting either in sand or metal moulds, and which,
notwithstanding any variations in the size of the projectiles, will always ensure
a large bearing surface to act on, and impart to it the rotatory. motion, and
will always cause it to be truly centred with the axis of the bore of the
gun. To effect these objects the figure in cross section of the grooves or
of that portion of the grooves which constitutes the driving side is described
by arcs of circles, the centres of which are placed in a circle (which I term
the generating circle) struck from the centre of the bore at equidistant

page_text: points around it, and so that a straight line drawn from a point on each
are equidistant or nearly equidistant from its two extremities to the centre
from which it is struck will be at right angles or nearly at right angles to a
line drawn from it to the centre of the bore. The diameter of this generating
circle will vary according to the number and depth of the grooves, but it should
always be within that of the bore.
My improvements in the tools for rifling consist of a method of constructing,
actuating, and securing the cutters in the rifling mandrel, so as to produce
grooves of the form herein-before described, as well as grooves of other forms.
For this purpose, for rifling guns of large size in which it would be inconvenient
to take a cut of the whole width of the groove, I employ one or more cutters
or frames carrying them, which are mounted on pivots or centres in the rifling
mandrel, corresponding to the centres in the generating circle, so that their
cutting edges will describe the arcs requisite to produce the form of rifling
before described, and the cutters or the frames carrying them are made to
turn on their centres or pivots by means of wedges or screws or other suitable
contrivance, by which they are set up so as to take a fresh cut as required.
In the case of small guns and small arms, in which a cut can be conveniently
taken the whole width of the groove, the cutting tool is made of a bar of steel
of any suitable form, carefully fitted into a slot made in the rifling mandrol, so
that its rear end abuts against one end and rests on the bottom of the slot,
and its front or cutting end rests upon a set screw, having a fine thread tapped
through the mandrel into the slot, and by which the cutter is set up to
take a fresh cut as required, and it is held down and kept steady by another
small screw, which is screwed into it, and passes through the mandrel. When
it is required to produce grooves of any form, composed of arcs of circles, the
front or cutting part of the cutting tool is turned in a lathe, hardened and
polished, the centres upon which it is turned being adjusted according to the
particular form of grooves required. If it is desired. to make them of the form
herein-before described it is turned upon centres corresponding to the centres
on the generating circle; but if grooves of the form of a single arc of a circle
are desired, the front of the tool is turned to a plain cylinder; for grooves of
other forms, the cutter is filed, ground, or otherwise made to the desired shape.
For the purpose of keeping the mandrel steady during the operation of rifling,
especially during the finishing cuts, I make a small recess in the mandrel, and
place therein a button of soft metal or alloy, which is forced into and moulded
to the form of the barrel, when the mandrel is drawn through.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Perceval Moses Parsons in the Great Seal Patent Office on
the 4th December 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PERCEVAL
MOSES PARSONS, of Blackheath, in the County of Kent, Civil Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifth day of June, in the year of our Lord
One thousand eight hundred and sixty-two, in the twenty-sixth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Perceval Moses Parsons, my Her special license that I, the said Perceval
Moses Parsons, my executors, administrators, and assigns, or such others as
I, the said Perceval Moses Parsons, my executors, administrators, or 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 ORDNANCE, AND IN TOOLS FOR RIFLING THE SAME, PARTS
OF WHICH IMPROVEMENTS ARE APPLICABLE TO SMALL ARMS," upon the condition
(amongst others) that I, the said Perceval Moses Parsons, my executors
or administrators, by an instrument in writing under my hand and scal, or
under the hand and seal of one of them, 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.
NOW KNOW YE, that I, the said Perceval Moses Parsons, 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, reference being had to the accompanying
Drawings, and to the letters and figures marked thereon, that is to say :-
My Invention consists, firstly, of certain methods of constructing ordnance,
the object of which is to enable guns to be made of larger calibre and greater
strength than can be obtained by the methods of construction now in use.
Figure 1 is a horizontal section, and Figure 2 a cross section, at A, A,
(Figure 1) of a gun constructed according to this part of my Invention. It
is composed of a tube a, a, made by preference of wrought iron, steel, or
homogeneous metal, which forms the bore of the piece; this tube is turned on

page_text: the outside and has a screw thread of suitable form cut on a considerable
portion of its length at the breech end, the remaining portion at the muzzle
being left cylindrical or by preference slightly conical; upon the screwed portion
of the tube a, a, a series of tubes of wrought iron, steel, or homogeneous
metal b, b, b, having a corresponding screw thread cut on their interior, are
screwed so as to encase the inner tube a, a, and upon the remaining portion
at the muzzle end a tube of wrought iron, steel, or homogeneous metal f, f, is
forced or shrunk, its outer end extending rather beyond and enclosing the end
of the internal tube a, a; if preferred, however, the whole of the internal
tube may have a screw thread cut on its exterior, and the tube f, f, instead of
being simply shrunk or forced on may be screwed on to it in the same manner
as the rings or tubes on the breech end. A screw thread is then in like
manner cut on the exterior of the tubes or rings b, b, b, and on a portion of
the tube ff, and another series of tubes or rings c, c, c, c, are screwed on,
and this process is repeated until the requisite thickness is obtained; thus in
the Drawing shewn, Figures 1 and 2, two more series or sets of tubes or
rings d, d, d, d, and e, e, e, are added, one of which carries the trunnions
9, 9. In some cases, more particularly for guns of small calibre, that portion
of the
gun at the muzzle may be formed in one instead of two or more layers
by making the internal tube at that part the requisite thickness, care being
taken that a portion of the thick part is well embraced by the adjoining ring
or tube screwed on to the breech end so as to unite both longitudinally. For
muzzle-loading guns the breech end is closed by a plug h, h, screwed into the
internal tube a, a, which is further secured by a breech screw i, i, behind it,
screwed into one of the outer rings or tubes.
for a breech-loader such modifications as the
arrangement required would have to be made.
together that each successive layer of rings or tubes will be in a state of
tension upon and compress the layer which it encloses, and this may be effected
either by making the outer rings or tubes the requisite amount smaller than
the inner tube and rings upon which they are intended to be secured and
expanding the outer rings or tubes by heat, then screwing them on and
allowing them to contract by cooling, or by making the tubes and rings slightly
conical and adjusting their sizes so that by screwing the rings on to their
intended position the desired initial strain will be produced. When the rings
or tubes encasing the inner tube are in separate pieces, as shewn in the
Drawing, it is essential that the different layers, or series of rings or tubes,
should break joint with one another (as shewn in Figure 1), by which means
they will impart longitudinal strength to each other and to the inner tube
Should the gun be intended
description of breech-loading
The tubes should be so put

page_text: forming the bore of the gun, which is a main object of this part of my Inven-
tion; and for this reason, when a number of separate rings are employed,
I prefer to use not less than two layers besides the inner tube forming the
bore of the gun, screwed together in the manner shewn and described; and.
should these provide the requisite longitudinal strength, and greater transverse
strength be required, an additional layer or layers of tubes or rings may be
simply shrunk or forced on without screwing. When only one layer is used
in addition to the internal tube it is desirable that it should be in one piece,
as, if in several rings, it will add but little to the longitudinal strength of the
gun and a main object of this part of my Invention would be defeated. This
construction would answer for guns of small calibre, but for large guns I
prefer to have more than one layer, in addition to the internal tube, with
separate rings, put together so as to break joint (as shewn and described),
both on the score of strength and of facility of manufacture. The tubes or
rings may be made by any of the well-known processes now in use, but I
consider this system of construction particularly applicable to guns built up of
tubes made on what is known as the coil system, that is, by coiling suitable
bars of wrought iron around a mandrel and then welding them into a tube or
ring, as it not only combines the separate tubes longitudinally, but also gives
additional security against faulty welds in the coils, and thereby imparts much
greater longitudinal strength to the gun than it is possible to obtain solely by
the adhesion or friction between the tubes or rings when these are simply
shrunk or forced on.
Figure 3 is a full-sized view, in section, of the kind of thread for the screw
which I should recommend; its exact form is not very material, but I con-
sider an angular preferable to a square thread, as when the rings are forced
or contract on to the tube or rings they surround, the action of an angular
thread would be to draw the parts together longitudinally as well as trans-
versely, and thus assist in carrying out the object of the Invention more per-
fectly, namely, that of providing longitudinal as well as transverse strength in
guns built up of separate pieces. I may here remark that I am aware that a
proposition has been made to construct guns by forming the body of the gun
of cast iron in the usual way, with walls half the thickness of the diameter
of the bore, and to screw thereon wrought-iron rings expanded by heat, but I
would have it understood that I lay no claim to this method of construction
unless the important features of my Invention for securing the requisite
longitudinal strength are combined therewith, neither do I consider that such
system would effect the ends aimed at by this part of my Invention, which
consists in building up the gun itself by screwing on to an inner tube, made

page_text: by preference of wrought iron, steel, or homogeneous metal, the requisite
number of tubes or rings, in the manner herein-before described, by which au
inner tube of very much less thickness than half the diameter of the bore may
be employed, and ample longitudinal as well as transverse strength obtained.
For the purpose of giving greater strength to guns which are composed mainly
of cast iron I bore out a recess, by preference of a conical form, at the breech
end of the gun, larger in diameter than the intended finished size of the bore,
but extending only a portion of its length, and I fit into the recess a tube of
wrought-iron, steel, homogeneous metal, or other suitable material accurately
turned to the shape and size of the recess, and secure it by a breech plug
screwed into the breech of the gun, if a muzzle-loading gun, or by a hollow
screw if a breech-loader. The tube may be in one piece of metal, or built up
of several, either by fitting two or more rings together, or by shrinking,
forcing, or screwing one or more tubes.or rings on to an inner tube or tubes.
Figure 4 is a longitudinal section, and Figure 5 a cross section at A, A,
(Figure 4) of a gun constructed on this system. a, a, is the body of the gun,
made of cast iron; b, b, is the tube of wrought iron, steel, or homogeneous
metal let into the conical recess at the breech end of the gun a, a, and secured
therein by the breech plug c. The tube is in this case composed of two layers,
as shewn, the outer one being intended to be shrunk or forced on to the inner
The tube has a breech plug d of its own, in addition to the breech plug
c, which secures it in its place. I consider this desirable in order to prevent
the explosive gases from getting between the end of the tube and the breech
plug c which secures it, and by acting on its larger area endangering its
security. I have not thought it requisite to shew a hollow screw for a breech-
loader, as its form and size must depend entirely on the description. of breech-
loading arrangement used, but its application, when required, will be under-
stood by those acquainted with the construction of guns of this description.
In some case I apply a tube of the description before named in combination
with a tube of wrought iron, steel, homogeneous metal, or other suitable
material, with which the gun is lined throughout the whole length of the bore.
one.
Figure 6 is a longitudinal section, and Figure 7 a cross section, at A, A,
(Figure 6) of a gun so constructed. a, a, is the body of the gun; b, b, is the
tube with which the gun is lined throughout; c, c, and d, d, are the tubes
applied at the breech end; e, the tube plug, and f, the breech plug which
secures the lining tube in its place. In constructing a gun of this description
I should first prepare the inner tube by turning it slightly conical, and
shrinking on to its breech end the tube c, c, and on to that the tube d, d, both
being carefully turned, and their sizes properly adjusted. The interior of the

page_text: gun being then bored out to a corresponding shape and size, the tube is
inserted and secured by screwing in the breech screw f. The degree of
tightness with which the internal tube is made to fit must depend on circum-
stances and the nature of the material used for the tube, as well as on the
quality of the cast iron, in reference to the amount of elongation each will
bear before exceeding its elastic limit, as well as the proportionate sizes of
each, and therefore no precise instructions can be given on this point; but the
degree of force with which the sides of the lining tube are pressed against the
sides of the cast-iron casing should be regulated so as to give to each its pro-
portionate share of work, or in other words, so that the extension of each
when under the strain of the discharge would bear about a relative proportion
to that of its elastic limit, and if anything I should be inclined to favor the
cast iron, its character being more uncertain than wrought iron or steel. As
a general rule, taking into consideration that wrought iron will admit of about
double the extension of cast iron in the same unit of length without straining
it beyond its clastic limit, I consider that a fair fit without much pressure
will be found to effect the object intended. It is, however, essential that the
ends of the lining tube b, b, (Figure 4) should bear well against the shoulder
or end of the recess at s, into which it is fitted, and against the face of the
breech screw c, so that being compressed between the shoulder at one end and
the breech screw at the other any strain thrown on the lining tube b, b, tending
to elongate it will be transferred to and resisted by the cast-iron body of the
gun; for the same reason, when a lining tube is used extending the whole
length of the gun, it should be turned down smaller at the muzzle end, so as
to form a shoulder to bear against the shoulder or end of the recess made in
the body of the gun for its reception, as shewn at s, s; (Figure 6). By this
arrangement a wrought-iron or steel tube of small thickness will be found to
add greatly to the transverse strength of the gun, and the recess to receive it
being taken out of the centre the sectional area of the body of the gun is so
slightly reduced that it will still possess ample longitudinal strength to support
the lining tube, by which combination guns may be made of great strength at
moderate cost, and existing cast-iron guns may be greatly strengthened. I am
aware that it has before been proposed to line cast-iron guns with tubes, and
to this of itself I lay no claim.
This part of my Invention consists in constructing and applying to cast-iron
guns, tubes of wrought-iron, steel, homogeneous metal, or other suitable.
material inserted at the breech end into a suitable recess, and secured therein
by a breech screw in such a manner that they will be confined longitudinally
by and receive longitudinal support from the body of the gun, and at the

page_text: same time relieve it of or absorb a large portion of the transverse strain, as
described; and I would have it understood that I do not confine myself to the
length or shape of the tubes, as shewn in the Drawing, as it may be desirable
in some cases to make them very considerably longer than shewn in Figure 4,
and probably it may be found to facilitate the manufacture to make the
external form of the lining tube a single core, as shewn by the dotted lines at g,
Figure 4, instead of the double cone shewn by the full lines in the same Figure.
My Invention consists, secondly, of a peculiar form of rifling which is appli-
cable to small arms as well as to ordnance, although it is particularly suited
to ordnance, as it enables hard metal projectiles to be used which do not
require to be machine-shaped, or made with greater accuracy than can ordi-
narily be obtained by casting either in sand or metal moulds, and which, not-
withstanding any slight variations in the size of the projectile, will always
ensure a large bearing surface to act on and impart to it the rototary motion;
and will always cause it to be truly centered with the axis of the bore of the
gun. To effect these objects, the figure in cross section of the grooves, or of
that portion of the grooves which constitutes the driving side, is described by
ares of circles, the centres of which are placed in a circle (which I term the
generating circle) struck from the centre of the bore at equidistant points
around it, and so that a straight line drawn from a point on each are equi-
distant or nearly equidistant from its two extremities to the centre from which
it is struck will be at right angles, or nearly at right angles to a line drawn
from that centre to the centre of the bore. The diameter of the generating
circle will vary according to the number and depth of the grooves, but it should
always be within that of the bore.
Figures 8, 9, and 10 are cross sections of the bore of guns rifled on this
system; and having six, three, and nine grooves respectively. The description
and the same letters refer to each Figure respectively. bis. the original circle
of the bore; g is the generating circle both struck from the same centre a;
c, d, e, is the driving side of the groove, and is an arc of a circle struck
from its centre f on the generating circle g, the position of which centre is
such that the line d, f, drawn from the point d equidistant or nearly equi-
distant from the two extremities c, e, of the arc c, d, e, will be at right angles
or nearly at right angles to the line f, a, drawn from the centre f, from which
the arc c, d, e, is struck to the centre of the bore a; the other side of the
groove may be of the same form as shewn, or of any other suitable form.
The other grooves are formed in like manner, the centres on the generating
circle 9. from which they are struck being arranged at equidistant points
around the centre of the bore a.

page_text: It will be seen that a greater or less number of grooves may be employed
at pleasure, and they can be varied as to depth and inclination by varying the
size of the generating circle g; thus if it be desired to make the grooves
flatter or less inclined to the circle of the bore 6, the generating circle g must
be smaller, and the contrary if a greater inclination be required, and they can
be so arranged as to leave more or less of the original surface of the bore, as
required. In practice, I should consider it desirable to slightly round off the
extreme angles at the bottom of the grooves, as shewn by the dotted lines in
Figure 9. The projectiles to be used with ordnance having this description
of rifling would have projections cast or made on them corresponding to the
form and twist of the grooves, but as much smaller as necessary to allow the
requisite amount of windage. For small arms, the projectiles can either be
made to the shape of the rifling or cylindrical, and made to fill the grooves by
expansion, as is well known.
In order to shew how this system of rifling will always ensure a full amount
of riffing surface to act on the projectile, I have, in Figure 8, added parts of
two projectiles of the same form, but differing in size considerably more than
would ever occur in practice if the two were cast from the same pattern;
these are colored red. No. 1 shews the larger projectile with its projection in
a central position in the groove, and No. 2, as it would be when being driven
out of the gun, and bearing against the rifling surface; No. 3 shews the
smaller projectile, with its projection in a central position in the groove; and
No. 4, its position when bearing against the rifling surface. By these
Diagrams, it will be seen that, notwithstanding the variation in the size of
the projectiles, although the windage is increased in the smaller one, a large
bearing surface is in each case obtained; and it will also be observed, that
the centre of the projectile must necessarily in both cases coincide with the
centre of the bore. I claim, under this part of my Invention, the peculiar
form of rifle grooves, whether for ordnance or small arms, as herein-before
described.
My improvements in tools for rifling consist of a method of constructing,
actuating, and securing the cutters in the rifling mandrel, so as to produce
grooves of the form herein-before described, as well as grooves of other forms.
Figure 11 is a longitudinal section, Figure 12 a cross section at A, A,
(Figure 11), and Figure 13 a cross section at B, B, (Figure 11), of a portion
of a rifling mandrel, fitted with an arrangement to rifle large guns with the
description of grooves herein-before described, in which it would be in-
convenient to take a cut the whole width of the groove at one time.
a, a, is
the body of the mandrel, having two recesses b and c made in it; the recess b

page_text: is intended to receive the shavings of metal cut off in the process of rifling, the
frame d is placed in the recess and it is supported and is capable of turning
freely on the centres or pivots e and f, which centres correspond with the
centres on the generating circle, from which the arc forming the profile of the
groove is struck. The frame d carries the cutting tool g of hardened steel, the
position of which is adjusted by the set screws h, i, and k; the frame d is pro-
vided with a pinion p, into which an endless screw a works to the spindle i³,
of which another pinion p² is attached, having another endless screw s²
working into it; this last endless screws is fixed on a rod, which passes
through a longitudinal hole in the rifling mandrel, and has a handle, cam, or
ratchet wheel attached to its outer extremity, for the purpose of giving
it rotatory motion, either by hand or by any other well-known means. By
turning round the rod, and with it the endless screw s³, the pinion p³ is made
to rotate, and carries with it the spindle i, to which it is attached, and with it
the endless screw 8; this in its turn acting on the pinion p, causes the frame d
to move about the centres e and f, and the point of the cutter to describe the
are m, n. The frame with the cutter being adjusted. to the position shewn
by the dotted lines (Figure 13), the mandrel is drawn repeatedly through
the gun with the requisite spiral motion, and the cutter is set up as much as
requisite at each stroke of the mandrel, by the arrangement for actuating it
herein-befere described, until the frame arrives at the end of its stroke in the
position shewn in Figures 12 and 13 by the full lines, when one side of one
groove will be cut to the proper form; the position of the gun being.
then shifted round its axis to the requisite position, the other grooves are cut
in like manner, and the opposite sides of the grooves can also be cut in like.
manner, either by shifting the gun end for end, or by using another similar:
frame and cutter made to work the reverse way, either on the same or another:
mandrel.
In the case of small guns and small arms in which a cut can be conveniently
taken the whole width of the groove at one time, I employ the following.
arrangement-Figures 14 and 15 are longitudinal sections of rifling mandrels:
with the cutting tool fitted to them, and Figure 16; a cross section at A, A,
(Figures 14 and 15); Figure 17, a cross section at B, B, (Figure 14); and
Figure 18, a cross section at C, C, (Figure 15). The cutting tool a, b, is
made of a bar of steel of suitable form, and carefully fitted into a slot shewn
in cross section at Figure 16 made in the rifling mandrel c, c, so that its rear
end b abuts against one end of and rests on the bottom of the slot, and its
front or cutting end a rests upon a set screw d, having a fine thread tapped
through the mandrel into the slot, by which the cutter a, b, is set up to take a
:

page_text: f
fresh cut as required, and it is held down and kept steady by another small set
screw e, which is screwed into it and passes through the mandrel. When it is
required to produce grooves of any form composed of arcs of circles, the cutting
part of the front of the tool a, b, is turned in a lathe hardened and polished,
the centres upon which it is turned being adjusted according to the particular
form of grooves required; if it is desired to make them of the form berein-
before described, it is turned upon centres corresponding to the centres of the
generating circle, but if grooves of the form of a single arc of a circle are
desired, the front of the tool is turned to a plain cylinder. For grooves of
other forms, the cutter is filed, ground, or otherwise made to the desired shape.
The cutting tools in all the foregoing arrangements are sharpened by simply
grinding away their front ends to a suitable angle.
In order to allow the cutting tool to be adjusted longitudinally, I sometimes
employ a set screw f acting against its rear end, and by providing a slot for
the set screw e to work in, the position of the cutter in the slot may be varied,
and in some kinds of rifling, where uniformity in a number of barrels is
important, the cutting tool .may by this means be set up as it is ground away
in sharpening, and its cutting edge always maintained in one position. For
the purpose of keeping the mandrel steady during the operation of rifling,
especially during the finishing cut, I make a small recess in the mandrel, and
place therein a button or piece of soft metal or alloy 9 (Figures 14 and 17),
which is forced into and moulded to the form of the barrel when the mandrel
is drawn through, or it may be of the form shewn in Figures 15 and 18, held
in its place by a couple of rivets or screws i, i, in which case the metal may be
harder, and it is then turned or fitted to the bore of the barrel; a set screws, s,
may be applied to set up the button or piece of metal g, as it is worn away,
and it also serves to adjust and tighten it so as to prevent the mandrel having
any shake in the barrel during the process of rifling.
I claim under this head of my Invention the general constructions and
arrrangements of rifling tools, whether for ordnance or small arms, substantially
as herein-before described.
In witness whereof, I, the said Perceval Moses Parsons, have hereunto
set my hand and seal, this Fourth day of December, One thousand
aight hundred and sixty two
P. M. PARSONS. (L.S.)