Improvements in Automatic Machine-guns.
Year: 1896

page_text: This Print is in accordance with the Original Specification as it stands after
Amendment (under Section 18 of the Patents, &c., Act, 1883) as allowed by
the decision of the Comptroller General of the 13th day of January 1899.
PROVISIONAL SPECIFICATION.
Improvements in Automatic Machine-guns.
We, THE HOTCHKISS ORDNANCE COMPANY LIMITED, of 49, Parliament Street,
London, S.W., a communication from abroad by Laurence V. Benét, Artillery
Engineer, of 21, Rue Royale, Paris, France, and Henri A. Mercié, Mechanical
Engineer, of 21, Rue Royale, Paris, France, do hereby declare the nature of this
invention to be as follows:-
These improvements relate to that class of gun in which a portion of the powder-
gas is utilized for operating the breech-action and feed-mechanism of the fire-
arm, and more particularly to that class of automatic machine-gun described and
illustrated in Letters Patent of Great Britain dated March 10 1896 bearing
No. 5426 and granted to the Hotchkiss Ordnance Co. Limited. It is evident,
however, that the improvements about to be described may be applied, in whole"
or in part, to guns operated by any well-known mechanical means.
FIRST IMPROVEMENT.
In machine or other guns operated by the powder-gas, as is the case in the,
aforementioned Letters Patent, the violence or speed with which the mechanism
will act depends upon the pressure of the gas acting upon the end of the motor
piston.
The object of this improvement is to provide means for regulating at will the.
pressure of the said gas. The means consist in providing, between the port which
admits the powder gas from the barrel to the cylinder in which the piston acts,
a chamber the capacity of which can be varied as required. Before the piston can
be moved by the said gas, it is thus rendered necessary that the gas should first
fill the said chamber after which it will act against the piston at a determined
pressure, the time necessary to develop such pressure and the magnitude of such
pressure depending upon the capacity of the said chamber.
SECOND IMPROVEMENT.
In machine-guns of the class under consideration, in which a large number of
rounds are fired in rapid succession from a single barrel, the successive discharges
add continual increments of heat to the barrel and as the radiating surface of
the latter is small, the temperature of the barrel soon reaches such a degree that
the metal becomes softened or even plastic, the interior surface becomes eroded,
the barrel expands and is thereby rendered unserviceable after a small number of
rounds. In machine guns of this class, it has been attempted to obviate this
difficulty by surrounding the barrel by a water jacket, with a view of absorbing
the heat in the water. This offers great tactical objections from the fact that

page_text: water must be carried for the service of the gun and that the steam evolved
renders the position of the gun visible from long distances. The construction
of a water jacket also offers great mechanical difficulties and complications, since
means must be provided for retaining the water whilst permitting the escape of
the steam at all angles of elevation and depression.
The object of this improvement is to obviate these inconveniences. The im-
provement consists in applying to the barrel a sleeve of steel or other metal having
heat-absorbing qualities, which is provided with annular ribs or with longitudinal,
helical or other shaped projections acting as heat-radiating surfaces.
THIRD IMPROVEMENT.
When a gun of the class under consideration is fired with powders giving a con-
siderable quantity of residue, this will collect in the front part of the gas cylinder
and if the gun is allowed to remain with the piston in its forward position for
any considerable time, this residue will harden and the piston cannot be moved
to the rear or cocked position by means of the finger piece connected to the said
piston.
The object of this improvement is to enable the piston to be readily started
when the gas cylinder so becomes clogged with residue.
To accomplish this object, a lever is mounted in the front part of the cocking
guard, the said lever being journaled in the guard and provided with a toe which
bears against a tang on the piston. When the lever is not in use, it can be held
in place against the cocking guard, wherein it remains without taking any part
in the movement of the mechanism of the arm. But should the piston stick in
its forward position and if the operation of the finger piece cannot move it, the
lever can be pressed downwards, the toc thereof then pressing against the said
tang and the piston being forced to the rear with great power:
FOURTH IMPROVEMENT.
A difficulty experienced with extractors used in this class of gun lies in the
fact that the claw of the extractor, in riding over the flange or head of the cart-
ridge in loading or in ejecting, will often detach small particles of the cartridge
metal which, lodging between the breech-block and the extractor, when the latter
is in the act of riding over the flange or head of the cartridge, will prevent the
extractor from returning to its normal position in contact with the breech-block
and from fully engaging with the head of the cartridge.
The object of this improvement is to provide simple and efficient means whereby
the extractor may perform its office independently of the presence of foreign
substances which may locate between the breech-block and the extractor.
To accomplish this object, a chamber is formed on the inside of the extractor
and affords a lodging place for any small bits of metal or other foreign bodies, as
above mentioned.
FIFTH IMPROVEMENT.
The sear described in the aforementioned Letters Patent, while readily dis-
connected and assembled, is unsatisfactory on account of its tendency to detach
itself from the piston when the latter is dismounted, falling to the ground with
the risk of loss and delay.
The object of this improvement is to securely attach to, and readily dismount
the sear from, the piston, while at the same time obviating the above mentioned
difficulty.
According to this improvement, the sear is not pivoted, as in the afore mentioned
Letters Patent, but is provided with a central dowel around which it can be turned.
In the piston is formed a cylindrical cavity for the reception of the dowel and
concentrically therewith is also formed a shallow cavity with undercut sides
corresponding to dovetailed sides of the sear. The shallow cavity is cut to such
a diameter with reference to the width of the piston that when the sear is placed

page_text: at right angles to the piston, the upper surface of the sear may touch the bottom
of the said shallow cavity. The sear consists of a body, a dowel as above stated
and a stud, all in one piece, the stud co-operating with a notch in the shallow.
cavity in the piston, so as to act as a stop for the sear.
SIXTH IMPROVEMENT.
This improvement relates to the shoulder piece, the object being to make it
separable from the breech cover, instead of, as in the aforementioned Letters
Patent, making it in one piece with the said cover. Means are provided under
this improvement for readily mounting and dismounting the said shoulder piece
independently of the means which connect the breech-cover to the gun.
SEVENTH IMPROVEMENT.
In the aforementioned Letters Patent is shown a piston tightly fitting the gas-
cylinder and provided with a gas-check groove with or without a spring or
other packing. It has been found that any error of alignment of the piston or of
assembling of the barrel or gas-cylinder would set up excessive friction between
the piston and the cylinder and prevent the proper working of the mechanism.
The object of this improvement is to provide an efficient gas-check between
the piston and the cylinder.
The end of the piston is provided with a separable head between which and
the end of the piston is fitted a loose gas-check ring; the said ring fits the opera
tive portion of the cylinder closely, whilst the piston may be made of much
smaller diameter. Hence there may be large errors in the alignment of the various
parts and the ring will still fit closely without excessive friction, as the ring will
follow the profile of the cylinder whilst the piston acts according to its own
alignment.
EIGHTH IMPROVEMENT.
It is not essential that the gas-check ring above set forth should fit the cylinder
with great nicety, as the pressure on the piston may he regulated by the first of
these improvements as already set forth, but if there be play between the said
ring and the cylinder, some of the gas will pass through the cylinder along the
piston and reach and foul the breech and feeding mechanism.
The object of this improvement is to prevent the said gas from eventually reach-
ing and fouling the said mechanism.
To accomplish this object, a baffle is formed on the piston for deflecting the
gas through suitable openings in, the cylinder into the open air.
NINTH IMPROVEMENT.
In the aforementioned Letters Patent are described means of assembling the
motor piston, with the breech-block and firing-pin.
Now this arrangement
developes the defect that if the three parts are assembled with the firing pin in
its forward position with reference to the breech-block and the breech-block in
its forward position with reference to the tang on the piston, the said tang will
fall behind the firing pin and the gun will be discharged before the breech is
closed and locked.
This improvement has for its object means for preventing an incorrect assem-
bling of the said piston and breech-block, so as to obviate the defect referred to.
This object is accomplished by forming guides on the firing tang of the piston
and by forming a corresponding slot in the breech-block, whereby the piston and
breech-block can only be assembled when the firing pin and firing tang are in
the forward and correct position with reference to the breech-block.
TENTH IMPROVEMENT.
The object of this improvement is to reduce to a minimum the effect of the
recoil upon the shoulder of the operator of the gun.
This object is accomplished by applying to the shoulder-piece of the gun a

page_text: special buffer consisting in a metal plate sufficiently thin to be resilient and of a
suitable shape to properly bear against the shoulder of the operator. At its w
extremities, the said spring plate is connected to the shoulder-piece of the gun
in such a manner that an open space for the play of the spring plate is left
between the inner face of the said plate and the corresponding opposite face of
the shoulder-piece, and such play between the buffer and its supporting pin or
pins, as will permit said buffer to yield under pressure or stress.
Dated this 18th day of December 1896.
Improvements in Automatic Machine-guns.
We, THE HOTCHKISS ORDNANCE COMPANY, LIMITED, of 49, Parliament Street,
S.W., London, a communication from abroad by Laurence V. Benét, Artillery
Engineer, of 21, Rue Royale, Paris, France, and Henri A. Mercié, Mechanical
Engineer, of 21, Rue Royale, Paris, France, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
These improvements relate to that class of gun in which a portion of the powder-
gas is utilised for operating the breech-action and feed-mechanism of the fire-
arm, and more particularly to that class of automatic machine-gun described and
illustrated in Letters Patent of Great Britain dated March 10, 1896 bearing
No. 5426 and granted to the Hotchkiss Ordnance Company, Limited. It is
evident, however, that the improvements about to be described may be applied,
in whole or in part, to guns operated by any well-known mechanical means."
In the accompanying drawings, we have only illustrated such portion of the
machine-gun of the class under consideration as is necessary for an intelligible
description of the improvements herein referred to.
In machine or other guns operated by the powder-gas, as is the case in the
aforementioned Letters Patent, the violence with which the mechanism will act
depends upon the pressure of the gas acting upon the end of the motor-piston.
One of the objects we have in view to accomplish is to provide means for regu-
lating at will the pressure of the said gas. The means consist, broadly speaking,
in providing between the port which admits the powder-gas from the barrel and
the cylinder in which the piston acts, a chamber such as hereinafter described and
means whereby its capacity can be varied as required, in the manner and for
the purpose hereinafter explained.
This improvement is shown in Figs. 1, 2, 3, 4, 5 & 6. Fig. 1 is a longitu-
dinal vertical section in which the gun-barrel and the cylinder are shown broken
away; the regulating device for the said chamber is in its extreme inward
position when the capacity of the chamber is reduced to its smallest amount.
Fig. 2 shows the same device in top view, but not in section, after it has been
adjusted so as to increase the capacity of the said chamber. Fig. 3 is a similar
view to Fig. 2 showing the manner in which the latch is fitted. Fig. 4 shows the
latch separately in external elevation; Fig. 5 is an underside plan of the same
and Fig. 6 is a section on the line 6, 6 of Fig. 4.
In order to facilitate the comparison with the drawings of the aforementioned

page_text: patent, we will here employ, in respect of the parts which have remained un-
changed, the same letters of reference as those employed in the said patent.
B, as in the said patent, is the barrel, C the cylinder of the motor-piston,
C the canal bringing the bore in communication with the cylinder C, and D is
the motor-piston.
The chamber of variable capacity is constituted by an extension 1 in a head 2
of the cylinder C, and opens into the chamber 3 inside the cylinder. The head 2
terminates in a screw-threaded tubular portion 4 into which is screwed a rod 5
having, at one end, a milled knob 6 and, at the other end, an obturating ring 7,
the outer face of which acts as a wall limiting the capacity of the extension or
opening 1. A tubular portion 8, concentric with the rod 5 and integral therewith,
moves along a scale 9 formed upon the tubular portion 4 and the conventional
division of which enables the gunner to ascertain the amount of the capacity
formed by the parts 1 & 3. In order to arrest the rod 5 in a desired position when
once the capacity of the chamber has been regulated, there is fixed to the tubular
portion 8 a spring latch 10 having a nose 11, see Figures 1, 4 & 5. The said
latch comprises a pivot provided with two projections 12, which, when the latch
is being put in place, as shown by the dotted lines of Fig. 3, pass through
notches 13 made in the opening for receiving the said pivot of the latch. By
imparting one quarter of a turn to the latch, the latter passes from the position
shown in Fig. to that shown in Fig. 2 and is thereby secured, its nose 11 en-
gaging a groove 14 in the tubular portion 4.
By screwing or unscrewing the knob 6, the obturating ring 7 can be caused to
advance or recede at will, consequently decreasing or increasing the capacity of
the space formed both by the extension 1 and the chamber 3.
It therefore follows that before actuating the motor-piston, the powder-gas
will first have to expand into the said space and fill it, after which it will act
upon the piston under a determined pressure, the length of time necessary for
the development of sucli pressure and the amount of the latter being a function
of the capacity of the said space.
In machine-guns of the class under consideration, in which a large number of
rounds are fired in rapid succession from a single barrel, the successive discharges
add continual increments of heat to the barrel and as the radiating surface of the
latter is small, the temperature of the barrel soon reaches such a degree that the
metal becomes softened or even plastic, the interior surface becomes eroded,
the barrel expands and is thereby rendered unserviceable after a small number of
rounds. In machine-guns of this class, it has been attempted to obviate this
difficulty by surrounding the barrel by a water-jacket, with a view of causing
the heat to be absorbed by the water. This offers great tactical objections from
the fact that water must be carried for the service of the gun and that the steam
evolved renders the position of the gun visible from long distances. The con-
struction of a water-jacket also offers great mechanical difficulties and complica-
tions, since means must be provided for retaining the water, whilst permitting
the escape of the steam at all angles of elevation and depression.
Another object we have in view to accomplish is to obviate these inconveniences,
for which purpose we shrink on to the barrel a sleeve made with a series of ribs of
steel or other metal for the purpose of absorbing the heat developed and exhorb-
ing it by radiation. This improvement is illustrated in Fig. 1, in which B is the
barrel over which is shrunk on a sleeve 15 of steel or other suitable metal having
annular ribs as shown, or having longitudinal, helical or other projections for
providing a large radiating surface. This sleeve therefore greatly increases not
only the surface of radiation, but the mass of metal that absorbs and transmits
the heat developed by the powder-gas. We make the interior diameter of the
sleeve. of smaller diameter than the part of the barrel on which it is assembled,
expand it by heat and slip it in place. When cooled. it contracts on the barrel,
compressing the latter. By this arrangement, if the barrel becomes softened by

page_text: heat, it is prevented from expanding owing to the compression exerted by the
sleeve.
."
When a gun of the class under consideration is fired with powder giving a con-
siderable quantity of residue, this will collect in the front part of the gas cylinder
and if the gun is allowed to remain with the piston in its forward position for
any considerable time, this residue will harden and the piston cannot be moved
to the rear or cocked position by means of the finger-piece connected to the said
piston.
Another object we have in view to accomplish is to enable the piston to be
readily started when the gas cylinder so becomes clogged with residue. To
accomplish this object, a lever is mounted in the front part of the cocking guard,
the said lever being journalled in the guard and provided with a toe which bears
against a tang on the piston. When the lever is not in use, it can be held in
place against the cocking guard, wherein it remains without taking any part in
the movement of the mechanism of the gun. But should the piston stick in its
forward position and if the operation of the finger-piece cannot move it, the lever
can be operated, the toe thereof then pressing against the said tang and the piston
being forced to the rear with great power. This improvement is shown in
Figs. 7, 8, 9 & 10, Fig. 10 being a cross section on the line 10, 10 of Fig. 7
D, as in the said patent, is the piston; D is the tang under the piston D and
having connected to it the cocking handle F; E is the main spring and A' is
the guard.
The lever 16 for forcing the piston to the rear is journalled in the guard A' and
on its axis 17 it carries a toe 18. At each end, the axis 17 is oppositely flattened,
as shown in dotted lines in Figs. 7, 8 & 9, for enabling the lever to be introduced
in place by causing the flattened portion to pass through an opening 19 on each
side of the guard A+ as shown in Fig. 9. The cocking handle F is pulled by
hand sufficiently toward the right to allow of the lever 16 being introduced and
placed in the normal position shown in Fig. 8. When it is not necessary to
make use of the lever, it is turned until it assumes the horizontal position shown
in Fig. 7, in which it is locked by a latch 20 engaging a corresponding recess in
the guard A, as shown in Fig. 10. In that position of the lever, its toe 18 is
inoperative and does not partake in the movements of the mechanism of the gun.
But if the piston D sticks in its forward position, i.e. the position it occupies in
Fig. 7, the lever 16 is to be disengaged and moved downward; the toe 18 presses
the tang D to the rear into the position shown in Fig. 8. The piston no longer
sticks and the operator can readily actuate the cocking handle F by hand.
A difficulty experienced with extractors used in this class of guns lies in the
fact that the claw of the extractor, in riding over the flange or head of the cart-
ridge in loading or in ejecting, will often detach small particles of the cartridge
metal which, lodging between the breech-block and the extractor, when the latter
is in the act of riding over the flange or head of the cartridge, will prevent the
extractor from returning to its normal position in contact with the breech-block
and from fully engaging with the head of the cartridge.
Another object we have in view to accomplish is to provide simple and
efficient means whereby the extractor may perform its office independently of
the presence of foreign substances which may locate between the breech-block
and the extractor. To accomplish this object, a chamber is formed on the inside
of the extractor and affords a lodging place for any small bits of metal or other
foreign bodies, as above mentioned. This arrangement is illustrated in full
size in Figs. 11 & 12, in which N is the extractor, the extremity of which alone
is shown.
is the claw or hook thereof. L is the breech-block.
On the extractor is formed a small shoulder 21 and a recess 22, the
former acting to keep the extractor at the proper distance from the breech-
block L and the latter acting as a cavity for receiving the particles of foreign
bodies hereinbefore referred to.
The sear described in the aforementioned Letters Patent, whilst readily dis-

page_text: connected and assembled, is unsatisfactory on account of its tendency to detach
itself from the piston when the latter is dismounted, falling to the ground with
the risk of loss and delay.
Another object we have in view to accomplish is to securely attach the sear
to, and readily dismount it from, the piston, while at the same time obviating
the above mentioned difficulty.
This improvement is illustrated in full size in Figures 13, 14, 15 & 16. Fig. 13,
which is an underside plan, shows the part of the piston to which the sear is
applied. Fig. 14 shows the first position assumed by the sear previous to its
being in place. Fig. 15 shows the sear in place and Fig. 16 is a section on the
line 16, 16 of Fig. 15. Moveover, the sear G is illustrated on a reduced scale 'in
Fig 7, in the position it assumes normally. In this arrangement, the sear G
is not pivoted, as in the said patent, but is provided with a dowel, preferably a
central one, around which it can be turned. In the piston D is formed a shallow
cavity, the transverse sides of which are dovetailed, and in the centre of that
cavity is formed a recess 25 'into which fits the dowel 26 of the sear G. The
sides of the sear, which are in an are of a circle, are likewise dovetailed to
correspond with the dovetailed sides or walls of the cavity 24.
In order to assemble the sear, it is first placed against the piston D in the
position illustrated in Fig. 14, with the dowel 26 engaging its recess 25, where-
upon one quarter of a turn is imparted to it in the direction of the arrow, so as to
cause it to assume the position shown in Fig. 15 in which it is parallel with the
piston. In order to stop the sear in position, it is provided with a stud 27 which
engages a corresponding hole 28 in the piston.
Another object we have in view to accomplish is to make the shoulder-piece
separable from the breech-cover, instead of, as in the said patent, making it in one
piece with the said cover, the object being to reduce the length of the gun for
transportation.
The device by means of which this object is accomplished is shown in Figs. 7,
17, 18, 19, 20 & 21. Fig. 7 illustrates the breech-cover J3 and the shoulder-
piece J which, in the said patent, are in one piece, whilst here they constitute two
separate pieces and A illustrates the receiver; in this figure, in which the
shoulder-piece J is shown broken away, the three parts are assembled and locked.
Fig. 17 illustrates the three parts assembled together, but the pin J' is in the
required position for admitting the shoulder-piece to be placed on or removed.
Fig. 18 is a plan of Fig. 17, in section on the line 18, 18. Fig. 19 illustrates the
three parts locked together as in Fig. 7, but the said parts are in external eleva-
tion instead of being in section. Fig. 20 is a plan of Fig. 19.
J6, as in the said patent, is the button for operating the pin J and is the
small stud which engages in a circular slot a³, shown in dotted lines in Fig. 19
and in full lines in the section Fig. 18.
The shoulder-piece has a T-shaped projection which fits into a corresponding
vertical slot in the breech-cover J; a lip 30 on each side of the projection 29
stops the downward movement of the shoulder-piece in the slot of the breech-
cover J3 when placing the shoulder-piece. The pin J is flattened at 31, Figs. 7,
17 & 18 and in the vertical wall of the shoulder-piece facing the said pin is
formed a recess 32, Figs. 7 & 17 in the form of an arc of a circle, the radius of
which is slightly greater than that of the radius of the pin J.
In order to assemble the parts, the breech-cover Js is first put in place, where-
upon the pin J is so presented opposite its opening that its stud be in front of
the groove 34, Figs. 18 & 19 formed in a receiver A; the pin then assumes a
position in which it deviates to the extent of 180° from the position shown in
Figs. 18, 19 & 20. The pin is then inserted and when its stud has reached
beyond the groove 34 and is in the circular slot a³, the button J6 is rotated in the
direction of the arrow Fig. 19 until the pin assumes the position illustrated in
Fig. 17 in which the flattened portion 31 is in a vertical plane. The shoulder-
piece J can then be put in place by sliding it down until its lips 30 rest upon the

page_text: breech-cover J3, the recess 32 being opposite the flattened portion of the piu J.
On turning the button Je to the extent of say 45°, but in the opposite direction, it
is made to pass from the position shown in Fig. 17 to that shown in Fig. 19, in
which latter it is stopped by a small lug j, as in the aforementioned patent.
In passing from one position to the other, i.e. from Fig. 17 to Fig. 19, the
flattened portion 31 of the pin J will be replaced by a solid portion which will
fill up the recess 32 and thereby lock the shoulder-piece J.
In the aforementioned patent is shown, in Fig. 7, a piston D nicely fitting the
gas-cylinder and provided with a gas-check groove D2 with or without a
spring or other packing. It has been found that any error of align-
ment of the piston or of assembling of the barrel or gas-cylinder would set up
excessive friction between the piston and the cylinder and prevent the proper
working of the mechanism.
Another object we have in view to accomplish is to provide an efficient gas-
check between the piston and the cylinder. An arrangement suitable for the
accomplishment is shown in Fig. 1 wherein D, as in the said patent, is the motor
piston and C the cylinder. At the end of the piston is screwed a head 35 between
which and the piston is fitted a loose gas-check ring 36. The external diameter
of the said ring fits the operative portion of the cylinder closely, whilst the piston
itself may be made of much smaller diameter. Between the central hole of the
ring 36 and the screw-threaded rod of the head 35 acting as an axis therefor, there
is a relatively large play so that there may be large errors in the alignment of the
various parts and the ring will still fit closely without excessive friction, as the
ring will follow the profile of the cylinder whilst the piston acts according to its
own alignment. It is not essential that the gas-check ring 36 above set forth should
fit the cylinder with great nicety, as the pressure on the piston may be regulated
by the improvement referred to in relation to Fig. 1 to 6 inclusive. But if there
be play between the said ring 36 and the cylinder, some of the gas will pass
through the cylinder along the fluted piston and reach and foul the breech and
feeding mechanism.
Another object we have in view to accomplish is to prevent the sail gas from
eventually reaching and fouling the said mechanism. The arrangement suitable
for the accomplishment of that object is shown in Fig. 1 and in Fig. 22 which
latter is a cross section of the piston D on the line 22, 22 of Fig. 1, and it consists
in forming on the piston, the diameter of which is less than the internal dia
meter of the cylinder C, one or more baffles or walls 37 by which the gas is
deflected and practically prevented from proceeding any further; said gas escap
ing into the open air through one or more openings in the cylinder, as soon
as the piston has moved sufficiently to the right to uncover the said openings.
In the aforementioned patent, the described means of assembling the motor-
piston D, Fig. 5, with the breech-block L and firing-pin M is apt to present the
following defect. If, as is shown in Fig. 23 of the accompanying drawings, the
piston D is not properly assembled with reference to the firing-pin M, that is to
say if the firing-pin is in its forward position with reference to the tang D of
the piston, instead of being in contact with the tang 18, as is normally shown
in Fig. 7, the gun will be discharged before the breech is closed and locked.
Another object we have in view to accomplish is to obviate an inaccurate
assembling of the three parts, in order that the serious defect above referred to
be avoided. The arrangement suitable for the accomplishment of that object
is shown in Fig. 7, also in Fig. 24 which is an underside plan, with reference
to Fig. 7 of a portion of the breech-block L, also in Fig. 25 which is a cross
section of Fig. 7 on the line 25, 25 and also in Fig. 26 which is a cross section
of Fig. 24, on the line 26, 26.
The front end of the slot 38, Fig. 24, through which pass the tangs D7, Ds of
the piston, is widened at 39, and in the thickness of the metal we make, on each
side of the said slot, a groove 40, 40. Moreover, we apply on each side of the
piston, a rib 41 the length of which is substantially equal to but no more than

page_text: the widened portion 39 of the slot 38. By means of this arrangement, the place
at which the tangs D', Ds can be introduced through the slot 38 is-restricted to
the widened portion 39. Assuming the firing-pin L to be in the position it
occupies in Fig. 7, the assembling of the piston will be possible and normal.
If, on the contrary, the firing-pin is, for instance, at the extreme end of its throw
toward the right, it will materially oppose any introduction of the said piston-
tangs and the assembling will be rendered impossible. It is therefore necessary
that the firing-pin be made to assume the position shown in Fig. 7 before the parts
can be assembled.
Another object we have in view to accomplish is to reduce to a minimum the
effect of the recoil upon the shoulder of the operator of the gun. A special
arrangement of buffer, suitable for the accomplishment of that object, is shown
in Fig. 19, 20 & 21. This arrangement consists of a plate 42 of steel or other
suitable metal sufficiently thin to be flexible and suitably shaped to bear properly
against the shoulder of the operator. At both ends, the said plate (which is
shown separately in Fig. 21 and is not shown at all in Fig. 20) carries à boss 43
in which is drilled a hole for the passage of a pin 44 connecting the said plate
to the shoulder-piece J. In order that the plate may yield under the pressure
exerted by the recoil, either one or both the holes for the passage of the pins 44
are enlarged, as is shown in dotted lines in Fig. 19 & 21.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, we declare that what
we claim is:
1. The hereinabove described improved method for controlling the pressure of
the powder-gas acting upon the end of the motor-piston D, consisting in forming,
between the port C which admits the Lowder-gas from the barrel B and the
cylindar C in which the piston acts, a chamber 3 the capacity of which can be
varied at will, reduction in pressure of the powder gas acting upon the end of
the motor-piston. D, being caused by so adjusting the parts as to increase the
capacity of the said chamber, 3, substantially as and for the purpose set forth.
2. In a breech-loading gun, the combination with the barrel B, cylinder C,
motor-piston D and canal C connecting the barrel to the cylinder, of a chambered
head 2, a tubular portion 4, an adjustable rod 5 having an obturating ring 7
and means for operating the said adjustable rod, substantially as and for the
purpose set forth.
3. In a breech-loading gun, the combination, with the barrel B, cylinder C,
motor-piston D and canal C connecting the harrel to the cylinder, of a chambered
head 2, a tubular portion 4, an adjustable rod 5 having an obturating ring 7,
means for operating the adjustable rod 5 and means for ascertaining and deter-
mining at will the capacity of the variable chamber 3, substantially as and for
the purpose set forth.
4. In a breech-loading gun, the combination, with the barrel B, cylinder C,
motor-piston D and canal C¹ connecting the barrel to the cylinder, of a chambered
head 2, a tubular portion 4, an adjustable rod 5, having an obturating ring 7,
means for operating the adjustable rod 5, means for ascertaining and determining
at will the capacity of the variable chamber 3, and means for locking the adjust-
able rod 5 when once the capacity of the chamber 3 has been adjusted, sub-
stantially as and for the purpose set forth.
5. In a breech-loading gun, the combination, with the barrel B, of a sleeve
fitted to or shrunk onto the said barrel and having formed on it radiating ribs 15,
substantially as and for the purpose set forth.
6. In a breech-loading gun, the combination, with a motor-piston D, of a
pivotted lever 16 having a toe 18 and a tang D on the piston, substantially as
and for the purpose set forth.
7. In a
breech-loading gun, the combination, with a motor-piston D. of a
lever 16 pivotted on an axis 17 in the guard A, a toe 18, a tang D' on the piston

page_text: and means for locking the lever 16 in position when not in use, substantially as
and for the purpose set forth.
8. In a breech-loading gun, an extractor N¹ having a shoulder 21 and a
22, constructed arranged and operating as shown and described for the
purpose set forth.
9. In a breech-loading gun, a motor-piston D on which are formed one or
more baffles or walls 37, as shewn and described whereby gas is practically pre-
vented from proceeding further and is caused to escape into the open air through
one or more openings in the cylinder, as soon as the piston has moved
sufficiently to uncover such opening or openings in the manner and for the
purpose set forth.
10. In a breech-loading gun, the combination, with the motor-piston D, of
ribs 41 working in grooves 40 of the breech-block L, substantially as described
and for the purpose of preventing inaccurate assembling of the parts as set forth.
11. In a breech-loading gun, the combination, with the motor-piston D, of
ribs 41 working in grooves 40 of the breech-block L, and a breech-block having
a slot 38 which is widened at 39 for the introduction and free passage of the
ribs 41, substantially as and for the purpose set forth.
Dated this 11th day of February 1897
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Chartered Patent Agent.