Improvements in and relating to Breech Mechanism for Automatic and other Guns.
Year: 1897

page_text: Date of Application, 31st Dec., 1897
Complete Specification Left, 26th Sept., 1898-Accepted, 25th Feb., 1899
PROVISIONAL SPECIFICATION.
.
PROVISIONAL SPECIFICATION.
Improvements in and relating to Breech Mechanism for Automatic
and other Guns.
6
We, ALBERT VICKERS, of 32, Victoria Street, Westminster, Steel Manu-
facturer, and LOUIS SILVERMAN, of Crayford Works, Crayford, in the County of
Kent, Engineer, do hereby declare the nature of this invention to be as follows:-
Our invention relates chiefly to improvements in Maxim" or automatic guns
of that class in which the breech-mechanism is operated by the pressure of the
gas escaping from the muzzle when the gun is discharged, various examples of
guns of this class being described in the Specifications of Patents granted to
Hiram Stevens Maxim, viz. No. 606 A.D. 1884, No. 4778 A.D. 1887, No. 6585
A.D. 1890 and No. 6591 A.D. 1890.
The said improvements comprise various novel features of construction and
combinations of the parts of the gun as hereinafter set forth.
The gun has a fixed barrel which is secured to the frame in the usual or any
convenient manner. It is in some instances provided with a water-jacket but
if desired the barrel instead of being circular is made rectangular in transverse
section, that is to sav it is a square or approximately square bar bored
longitudinally, and has the metal perforated transversely at intervals throughout
its length at the sides of the bore to form channels or spaces for the passage of the
air, whereby it can be kept cool without the use of a water jacket.
This
The lock is made in two parts ciz. a forward and a rear portion. The forward
portion which forms the breech block proper is fitted on its face with a vertically
sliding cartridge-carrier such as that commonly used in Maxim guns.
carrier receives the cartridges from the fced-belt and inserts them into the barrel
and also serves to extract the cartridges from the belt and the spent cartridges
from the barrel and transfer the former to the barrel and the latter to the exit
aperture. The rear part of the lock is jointed or pivoted to the forward part; at
the moment of firing it serves as a strut between the forward part and the rear
end of the frame to close the breech and support the cartridges in the barrel, and
after the discharge, moves clear of its support or abutment to permit the opening
of the breech, the extraction of the spent cartridge and the insertion of a fresh
cartridge. The rear-end surface of the strut and of the abutment or portion
of the frame against which it is supported are parts of a circle struck from a
centre below the said pivot so that when depressed the said strut will move freely
clear of the said abutment.
The mechanism for effecting these operations in an automatic gun is as follows
viz.: The muzzle end of the barrel has an attachment consisting of a cap formed
in one piece and communicating with a small cylinder and provided with a
sleeve or clamp whereby it is secured on the end of the barrel. The cap has
in its forward end a hole for the passage of the bullets and communicates by a
transverse passage with the forward end of the cylinder so that as the bullet
leaves the gun the gas from the barrel enters the forward end of the cylinder.

page_text: The said cylinder is fitted wih a piston attached to the end of a rod which extends
through a tube, below the barrel towards the breech end of the same. The tube
contains a spiral spring which returns the piston to its forward position after
each discharge of the gun. The cylinder is provided with a discharge aperture
to permit the escape of the gas after each stroke. The rear end of the piston-rod
is secured to a sliding piece which is termed the action bar and is arranged to
move longitudinally in the frame below the strut. This action bar has in its
forward portion a longitudinal aperture or slot through which the spent cartridges
can descend to escape from the gun. Its rear end is a flat plate which is formed
on its upper side with a central rib terminating at its rear end in a projection
which is designed to engage with inclined surfaces on the under side of the
pivoted strut to thereby depress and raise the same in the recoil and return move-
ments of the action bar. The rear end of the strut has a recess with inclined
surfaces on its upper and lower edges. In the first part of the recoil movement
the projection on the action bar first rides upon the lower inclined surface of
the said recess and thereby depresses the rear end of the strut bringing it down
clear of its support or abutment so that in continuing its recoil the said action
bar can push the strut backward thereby opening the breech, the said strut in this
backward movement being guided by means of longitudinal grooves in a rear-
ward extension of the frame.
In the first part of the return movement of the action-bar the strut moves
forward with the said bar until its rear end comes in front of the abutment on
the end of the frame; the upper edge of the projection on the said action-bar then
acting on the upper inclined surface of the recess of the strut raises the latter.
I te said upper edge of the projection has a peculiar formation. That is to say
its forward portion is inclined at such an angle to the horizontal direction of
its movement, that by its action on the inclined surface of the strut, it raises
the latter nearly but not quite sufficient to close the breech; it thus leaves the
breech block in such a position that the cartridge-carrier fitted to the face of the
block can slide up freely thereon into engagement with the cartridges in the belt
and in the barrel, the block not being forced completely home till the completion
of this movement of the carrier. For this purpose the upper part of the edge
of the said projection is inclined to the horizontal line at a smaller angle than
the forward part, and the inclines are so arranged that this upper part of the edge
of the projection begins to act on the strut at the completion of the aforesaid
movement of the carrier thereby forcing the breech block securely home. The
edge of the said projection terminates in a horizontal portion on which the
lower surface of the strut rests when the breech is completely closed so that there
is no possibility of the same having its security diminished by vibration of
the gun in action. If desired a spring may be provided in the underside of the
cover or otherwise arranged to act upon the lock in the first part of its return
movement.
The pivoted strut or rear portion of the lock carries the firing pin in a central
hole. The forward end or head of the said firing pin is preferably made of rather
unusually large diameter and is tapered to the point which is so arranged that
if driven forward when the breech is properly closed the point will pass through
a small aperture in the carrier; but, when the gun is cocked the point lies in a
cavity of a diameter somewhat larger than that of the forward end of the pin
This arrangement constitutes a safety device as, when the strut is depressed, the
angle which the firing pin makes with the face of the breech-block brings the
point behind the shoulder at the front end of the said cavity and therefore the
premature striking of the cartridge in the gun by the firing pin will be impossible.
The tail or rear portion of the firing pin is surrounded by a spiral spring arranged
in the central hole in the strut to operate in the usual manner when the pin
is released by the sear. The firing pin is cocked in the recoil movement of the
lock by means of a vertical arm on the action-bar which arm engages with a
shoulder on the firing pin and forces it back into engagement with the sears.

page_text: The firing pin then moves with the lock in its recoil and forward movements till
the moment when the breech block is closed as above described, at which moment
the pin is released and driven forward to strike the cartridge in the barrel.
There are two sears one operated automatically and the other by means of the
trigger which is arranged and connected with a trigger bar as described in the
specifications of some of the patents granted to the said Hiram S. Maxim as
aforesaid, so that while the trigger is held back the gun will continue to fire
automatically but when the trigger is released the gun will cease firing.
arm that
The cartridge feed-belt is moved forward through the gun by the following
mechanism, viz.:-Over the rear end of the barrel is arranged a horizontal lever
that is to say a lever on a vertical pivot about which it can oscillate in a lateral
direction. Its pivot-pin drops into a socket forward of the feed-belt in the part
of the frame in which the barrel is fixed. Above the said lever is arranged a
longitudinally sliding bar the rear end of which terminates in an
projects downward into a socket in the breech-block so that the said bar
participates in the to and fro movements of the said breech-block. The said bar
has in it a cam-groove or slot into which projects a stud on the said lever. The
said groove is so formed that as the bar moves longitudinally it acts on the stud
of the lever and thereby imparts to the said lever its lateral oscillating movements
whereby the feed belt is moved forward across the feed-box one step for every
discharge of the gun. Any of the arrangements of pawls described in the aforesaid
specifications or used in "Maxim" guns for pushing the belt forward and for
preventing its return may be adopted. But to avoid the difficulty which has
been heretofore experienced in the working of automatic guns by reason of the
slipping of the pawls from their engagement with the feed belt and the con-
sequent temporary stoppage of its action we provide the following device viz. In
the rear or free end of the said lever is a slot or aperture into which projects
the nose of a spring pawl pivotted to the lever. The lower edge of the nose
projects downward from the said slot into a position to engage with the cartridge
or projection of the belt immediately below it and thereby move the helt forward
one step for every forward oscillatory or vibratory movement of the lever. The
nose is bevelled on its rear side so that as the lever moves back after each of such
feed movements the nose is raised and passes over the next cartridge or projection
of the belt and then drops behind the same in the position to act thereon and
push the belt forward in the next oscillation of the lever. To permit this action
of the pawl the nose is; so formed and arranged within the slot of the lever
that it is capable of a slight lateral free movement or "lost motion" relatively
to the lever, in the oscillations of the latter. The object of this arrangement
is that a small projection on the rear of the nose may, when the latter is down,
enter a groove or notch in the rear side of the slot and thereby hold the nose
down while it exerts its action on the belt, and may then leave the groove and
release the nose; that is to say: In the feed movement of the lever the latter is
permitted by the "lost motion to engage with the projection on the nose and
on the completion of the feed movement, the lever in its backward movement can
by reason of the "lost motion" move far enough to withdraw the groove or notch
from the projection on the nose before commencing to move the pawl, thereby
permitting the nose to drop as above described.
"
For operating the cartridge carrier on the face of the breech block, I employ a
lever arm pivoted at the joint of the lock, the forward end of which lever is
inserted in a slot near the lower end of the carrier. Near the pivot the said
lever-arm is formed with a corner or heel which lies in the path of a shoulder on
the action bar so that the latter in its return or forward movement raises the
said carrier to its highest position at the moment when, as above set forth,
the breech is nearly but not quite completely closed.
In the recoil of the lock the carrier is guided by grooves in the sides of the
frame so that it first moves backward to extract the cartridges from the belt and
from the barrel and then descends to bring the first down to the barrel and the
other into the position to be ejected from the gun.

page_text: For starting the firing of the gun we preferably provide an external oscillating
handle which is adapted to act upon a projection on the action bar and thereby
actuate the mechanism by hand.
It is obvious that the above described breech mechanism may be operated by
hand instead of automatically. For this purpose we may dispense with the
muzzle attachment and its adjuncts and we provide the mechanism with a lever
or handle and crank suitably arranged for effecting the required movements of
the parts.
HASELTINE, LAKE, & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicants.
Improvements in and relating to Breech Mechanism for Automatic
and other Guns.
We, ALBERT VICKERS, of 32, Victoria Street, Westminster, Steel Manu-
facturer, and LOUIS SILVERMAN, of Crayford Works, Crayford, in the County of
Kent, Engineer, 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: -
This invention relates chiefly to improvements in automatic or Maxim guns
of that class in which the breech-mechanism is operated by the pressure of the gas
escaping from the muzzle when the gun is discharged.
The said improvements comprise various novel features of construction and
combinations of the parts of the gun as hereinafter set forth.
The gun has a fixed or stationary barrel which is secured to the frame in the
usual or any convenient manner. It is in some instances provided with a water-
jacket but if desired we may dispense with the water-jacket and form the barrel
square or approximately square in cross section with numerous transverse channels
or holes extending through the metal walls thereof to form passages or channels
for the surrounding air to pass through and cool the barrel.
The breech block or lock of the gun is made in two parts viz. a forward and
a rear portion. The forward portion or breech block proper carries a vertically
sliding cartridge carrier similar to that ordinarily employed in a Maxim gun
and the rear portion is jointed or pivoted to the forward portion so that it is
capable of a slight amount of vertical movement independently of the aforesaid
forward portion. When the breech is closed this vertical movement of the rear
portion enables it to come in front of fixed projections or abutments and thereby
act as a strut to securely hold the breech closed at the moment of firing.
movement of the said rear portion or strut is effected by a peculiarly shaped rib
or projection on a sliding piece termed the action bar, acting in conjunction
with inclined surfaces or projections on the strut as hereinafter explained.
The
The action bar is operated by a piston connected therewith by a rod and working
in a cylinder which communicates with the muzzle of the gun barrel so that the
escaping gases from the barrel, after the projectile leaves the gun, can enter said
cylinder and actuate the piston. A spiral spring surrounding the said piston
rod acts to return the parts to their firing position after each rearward movement
of the piston.
For operating the cartridge carrier we employ a pivoted lifting lever which
is carried by the forward portion of the lock and engages at its front end with

page_text: a slot in the said carrier. The said lever has a lateral pin which slides in the
usual cam path in the frame of the gun as the lock reciprocates. The said lever
also has a heel against which a shoulder on the action bar strikes during the
closing of the breech and thereby raises said carrier into its highest position just
before the completion of the final closing movement of the breech block under
the action of its strut.
For feeding the cartridge belt through the gun we employ above the feed-box
a lever having a vertical pivot about which it can oscillate in a horizontal plane.
Above the said lever is arranged a longitudinally sliding bar or plate which
receives its motion from the reciprocating lock. This plate has an inclined or
cam groove with which a stud on the free end of the aforesaid lever engages, sa
that as the plate slides to and fro, oscillatory movement is imparted to the lever.
The said plate can be very readily detached from the feed-lever and the breech
block when desired.
To avoid the difficulty that has heretofore been experienced by reason of the
slipping of the feed pawls from their engagement with the cartridge belt, we
provide the said feed-fever with a spring pawl which is capable of performing a
fimited independent movement with respect to the feed-lever, whereby said pawl
permitted to rise vertically during each outward stroke of the feed lever but
is restrained from so doing during each inward stroke of the said lever.
We also provide the gun with an external crank handle for starting the firing
or working the gun manually, the said handle being so connected with the
action bar that it remains stationary during the firing.
In order that the said invention may be clearly understood and readily carried
into effect we will proceed to describe the same more fully with reference to the
accompanying drawings in which―
Figure 1 is a side elevation,
Figure 2 a central longitudinal section, and
Figure 3 a plan of an automatic gun constructed in accordance with our
invention.
Figure 4 is a plan of the gun casing with the upper plate or cover removed.
Figure 5 is a rear view of the gun casing with the hinged end piece removed.
Figure 6 is a vertical section on the line 1, 1, of Figure 2, looking toward the
front.
Figure 7 is a vertical section on the line 2, 2, of Figure 2 looking toward the
rear.
Figure 8 is a horizontal section, taken approximately on the line 3, 3, of
Figure 1 with only so much of the internal parts shewn, as is necessary to clearly
illustrate the manner in which the external handle is coupled to the action bar
so that said handle remains stationary during firing.
Figure 9 is a plan of the action bar detached.
Figure 10 is a plan of the trigger bar detached.
Figures 11 and 12 are detail sectional views of the hinge of the aforesaid
hinged end piece.
Figure 13 is a side elevation, Figure 14 a longitudinal section, Figure 15 a
plan, Figure 16 an underside view, Figure 17 a rear end view, and Figure 18 a
front end view of the breech-block or lock detached and drawn to an enlarged
scale.
Figure 19 is a side elevation, and Figure 20 a plan of the firing pin detached.
Figure 21 is a plan of the head of the firing pin detached.
Figures 22, 23 and 24 are respectively a plan, an edge view and an underside
view of the cartridge feed lever and its spring pawl.
Figures 25, 26 and 27 are transverse sections taken substantially on the
line 4, 4, of Figure 23 looking toward the right and shewing the feed lever and
its spring pawl respectively in the position they occupy when the feed lever is
commencing its outward stroke to bring the pawl into engagement with a
cartridge in the feed belt, when said pawl is passing over said cartridge and when

page_text: said pawi has passed over said cartridge and the feed lever is commencing to
perform its inward stroke.
Figures 28 and 29 are respectively a central longitudinal section and an under-
side view of the sliding plate by which the cartridge-feed lever is oscillated.
Figures 30, 31 and 32 are longitudinal sections, shewing the breech block or
lock and the action bar respectively in the position they occupy when the breech
block is fully closed and locked, when it is disengaged, and when it is fully
retracted.
Figure 33 is a transverse section and Figure 34 is a horizontal section of a gun
barrel formed with transverse channels in its walls for the passage of air to keep
the barrel cool without a water-jacket.
Figures 35 and 36 are similar views of a modified arrangement of the said air
channels.
Figure 37 is a central longitudinal section of a slightly modified form of the
gun illustrated by Figure 2.
Like reference letters indicate similar parts in all the figures.
AA are the side plates of the frame or casing enclosing the breech mechanism;
A is the hinged top plate or cover and A2 the hinged rear end piece. B is the
barrel. C is the breech block or lock. D is the action bar and E is the water'
jacket.
Referring more particularly to Figures 1 to 32:-
ce (Figures 13 to 18) are the two portions of the breech block or lock hinged
together by a pivot pin c². The forward portion or breech block proper c is pro-
vided with the vertically sliding cartridge carrier which performs the various
functions necessary for transferring the cartridge from the feed belt to the barrel
and for extracting and ejecting the spent cartridge from the barrel, like the
ordinary sliding carrier of a Maxim gun. The said forward portion c is formed
with side ribs which engage with horizontal grooves a in the side plates A
and guide the lock in its reciprocating movements as is well understood. The
said forward portion is also provided with depending lugs through which
passes a pin carrying the safety sear 7, the firing sear and the lifting
lever c³. The last mentioned lever is situated between the other two levers and is
provided with a curved nose c10 that engages with a slot c¹ in the carrier. It is
also formed with a heel c2 which is acted upon by the action bar D as hereinafter
explained. The portions ce¹ of the lock are made hollow for the reception of
the firing pin and its spring c¹³. The firing pin is jointed that is to say it
comprises a body portion c¹ and a head c15 (see Figures 19, 20 and 21) having a
cylindrical tee-piece c¹6 which is adapted to engage with a corresponding recess
in the body c4 and thereby connect these parts together. The engagement is
effected by sliding the tee piece ct lengthwise into the aforesaid recess in the
body c¹ At the front lower part or margin of the said recess is a shoulder c¹7
which supports the head c¹5 in an approximately horizontal position opposite the
conical hole c¹8 in the carrier when the latter is fully raised (Figure 14). The
upper part or margin c¹ of the said recess is unprovided with a shoulder and
therefore renders the head of the firing pin free to turn slightly upward about
its tee-piece, so that in the event of the said head entering the conical hole c18
out of alignment with the detonator of the cartridge, it will readily adjust itself to
the proper position by the guiding action of the conical wall of said hole. This
manner of connecting the parts of the firing pin also enables the head c¹ to be
readily disconnected, if it becomes broken, and replaced by a fresh one.
body portion of the firing pin is formed with a longitudinal slot 20 through
which the pin connecting the portions ccl together passes and retains the firing
pin in place, without restraining its cocking and firing movements. The lower
part of the body portion c¹ is provided with a shoulder which projects through
a slotted opening in the underside of the lock. With this shoulder the noses of
the safety sear 7 and the firing sear engage, under the action of their springs,
when the firing pin is fully cocked. The opposite ends or tails of the aforesaid
The

page_text: pivot pin.
When
sears cc, respectively, are acted upon by the action bar and trigger bar as here-
inafter explained. The rear portion or strut e¹ of the lock has lateral projections
or lugs, which are adapted to engage with abutments a¹ on the side plates A
when the said strut is elevated into the raised position represented in Figures 2
and 30. A very rigid support to the forward portion of the lock is thereby
obtained at the moment of firing, which effectually resists the rearward stress
tending to force the lock backward. a3 is a bridge piece which extends between
and preferably forms part of the abutments a¹ and serves as a stop to limit
the extent of upward movement which the strut c¹ of the lock can perform, the
The
said strut being provided with a projection to come against said stop.
working faces of the abutments a and the lateral projections or lugs are
inclined or bevelled to permit of their sliding on each other when the said
strut c¹ turns about its pivot & in bringing them into and out of engagement. If
preferred these working faces may be curved, the face of the projections or
Jugs then being an arc of a circle struck from the central point of
the pivot pin and that of the abutments being an arc of a
circle struck from a point somewhat below said
the strut c¹ assumes its lowered position (Figure 31) the aforesaid lateral
projections or lugs come into a position to slide beneath ribs a³ on the
interior of the hollow hinged end piece A3 and in the rearward movement of the
lock these ribs act as guides for the said strut and prevent it from rising during
the return or forward movement of the lock as hereinafter explained. The under-
side of the said strut is provided with two projections which are acted upon
by a rib or projection d on the action bar as the latter performs its reciprocating
movements. The projection 2 has an inclined surface against which a nose d
on the said rib d strikes (see Figures 30 to. 32) as the action bar slides backward,
and thereby acts first to depress the strut c and disengage it from the abut-
ments (Figure 31) and then to withdraw the lock from the barrel to open the
breech (Figure 32). The upper portion of the said rib d is of such shape that
when the strut c¹ is depressed it will lie in the space or recess existing between
the two projections 22 (Figure 31). On the return movement of the action
bar the edge of the rib will bear against the rear inclined portion of the
projection and as the strut cannot at such time rise by reason of the
ribs a, the lock is pulled forward with the action bar until the lugs on the strut
escape from the said ribs a³ and from the underside of the abutments a¹. The
pressure of the edge of the rib on the said rear inclined portion 27 of the
projection, as the action bar terminates its forward movement, then raises the
strut and brings the working faces of the lugs again into engagement with
the working faces of the abutments a¹. It is not however until the upper
surface of the said rib slides on the underside of the projection as the
action bar I completes its forward movement that the final upward movement
of the strut and the complete closing of the breech take place, the said surface ³
being for this purpose inclined slightly to the horizontal. The object of this
movement is to permit the carrier to reach its highest position just before
the aforesaid final closing movement of the lock is completed, so that at such
time the said carrier will not be jammed too rigidly against the breech end of
the barrel and be thereby prevented from reaching its fully raised position. The
said surface 3 by firmly pressing against the underside of the projection 25 also
rigidly maintains the strut in its raised position so that there is no possibility
of the same having its security diminished by vibration of the gun in action.
The aforesaid rib is provided with a neb d which lies in front of a shoulder
on the underside of the body of the firing pin and during the first portion of the
rearward movement of the action bar, (that is to say before the nose reaches
the incline of the projection ) such neb pushes back the firing pin against
the resistance of its spring, until the sears cc engage with the shoulder 21 and
keep the firing pin cocked. The vertical movements of the cartridge carrier are
controlled by a pin c on the lifting lever acting in conjunction with the

page_text: ordinary cam with which one of the side plates A is provided as is well
understood. The elevation of the said carrier is effected, however, by a shoulder ‹³
on the action bar (Figure 9) striking the heel 12 as the said bar performs its
forward movement and just before the strut terminates its upward movement
under the action of the inclined surface d³ on the projection 25 as already ex-
plained. The action bar is also formed with another shoulder which acts upon
the tail of the safety sear and disengages its nose from the firing pin, when
said action bar completes its forward movement. The said action bar has an
elongated aperture or slot d therein, through which the empty cartridge cases
fall from the gun as they are extracted and ejected. In order to avoid any
liability of the said empty cases getting in front of the action bar and impeding
the proper working of the gun, said bar is formed at its forward end with a
block having a downward inclined surface facing the slot d. The said
block is of such dimensions in cross section as to practically fit the space within
which it works, immediately below the barrel so that as the action bar moves
rearwardly, the said inclined surface of the block 8 would strike an empty
cartridge case and throw it downwardly from the gun, in the event of its not
having already escaped through the slot .
are grooves in the side
plates A within which the said action bar slides and by which it is guided during
its reciprocating movements.
The tail of the firing sear is prolonged through the slot d in the action bar
so as to lie in proximity to a protuberance f on the trigger bar F when the
breech is closed. This trigger bar is adapted to slide in grooves as a formed in
the side plates A when the trigger fl is pulled, a spring returning said plate
to its original position when the trigger is released. When the trigger is pulled
the aforesaid protuberance f comes beneath the tail of the firing sear and by
raising it thereby trips this sear and so releases the firing pin and fires the
gun. It will be obvious that so long as the trigger is held in its pulled position,
the gun will continue to fire automatically. For the purpose of preventing the
trigger from being pulled when the hinged end piece A is turned down to
uncover the breech end of the gun casing, the said trigger bar is formed with a
cavity or recess f³ with which a correspondingly shaped portion or cam piece a
on the hinged end piece A2 near its pivot A³, engages when said end piece
is turned down as represented in Figure 12. The trigger plate then remains
locked and the gun cannot be fired until said cam piece a is removed from the
cavity or recess f³ in the act of closing the end piece A2 as shewn in Figure 11.
In order to impart to the action bar D the requisite movements for actuating
the breech mechanism, it is connected by a rod 11 to a piston D² which is arranged
within the gas cylinder D³ (see Figures 2 and 7). This cylinder is located below
the barrel and communicates near its front end, by an opening +, with a
chamber 1 surrounding the muzzle of the gun barrel. The front of this chamber
is closed by a screw plug D6 formed with a longitudinal hole for the passage
of the projectile, such plug serving to contract the outlet for the gases of discharge
entering the said chamber, so that they will be caused to enter the cylinder 13
and effectually act upon the piston D2. By so doing they force the piston rear-
wardly against the resistance of the spring 1 that surrounds the rod D¹ and
also shift the action bar rearwardly, whereby the lock is actuated as hereinbefore
explained; the reaction of the spring I returning the piston and the action bar
to their original position after each rearward movement. The, aforesaid spring 17
is completely enclosed by a casing D8 extending from the cylinder 13 to a fixed
sleeve D with which the gun frame is furnished and through which the said
rod I slides during its reciprocations. The said casing is provided with lateral
openings Do". The opening 110 permits the gas within the cylinder to escape
when the piston is forced back far enough to uncover it, and the opening D
enables atmospheric air to enter the cylinder as the piston returns to its original
position and avoids the retardation of the piston's forward movement, which
would otherwise take place by the formation of a partial vacuum behind it.

page_text: G (Figures 22 to 24) is the horizontal lever which forms part of the cartridge
feed mechanism. It is provided with a vertical pivot pin g which loosely fits
a hole formed for its reception in the gun frame at a point forward of the feed-
box J. Near the opposite end of the said feed lever and on the upper side thereof
is a stud g which engages with an inclined or cam groove h in the underside of.
the rectilinear sliding plate H (Figures 28 and 29) which is superimposed above
the said lever, as best seen in Figure 2. This plate has a depending arm h
which engages with a socket or recess in the forward part of the lock. As
the lock reciprocates it imparts longitudinal movement to the said plate which
slides on ledges as as in the upper edges of the side plates A. By the action of
the inclined groove h on the stud g¹ the feed lever G is caused to oscillate and
give a step by step movement to the cartridge belt by a pawl G₁. It is to bo
observed that this plate is not fixedly connected to the feed lever and the breech
block but is held in place by the hinged cover A¹, so that by opening said cover
the plate can be immediately detached from the gun if so desired.
Heretofore difficulty has been experienced by reason of the slipping of the feed
pawl from engagement with the cartridges or projections of the belt during the
feeding movement of the pawl. In order to overcome this difficulty we construct
the said pawl of a thin strip so as to be resilient and we pivotally connect if at
one end to the feed lever by a screw pin 92. Its opposite end is curved and
terminates in a bevelled nose or pawl proper g³ having an upward projection or
head adapted to lie in a slot in the free end of the feed lever. The said
spring pawl also provided with a lateral extension 96 that projects through a
lateral opening g' in the front side wall of the said slot 95. When the said
feed lever performs an outward stroke, that is to say, a stroke in the direction of
the arrow in Figure 4, the nose g3 (owing to the flexibility of the steel strip of
which the pawl G₁ is composed and the bevelled shape of the said nose) rises
over the cartridge or projection on the feed-belt as seen in Figure 26, and
brings the projection g into the slot g5 so that the feed lever and the pawl move
outward together. Then, when the said nose g³ reaches the opposite side of
the cartridge, the flexibility of the said steel strip causes the nose to descend
behind the cartridge (Figure 27) and on the inward or return stroke of the feed-
lever, the latter moves a short distance without the pawl which is engaging with
a cartridge as aforesaid. The projection or head g of the pawl therefore enters
the lateral opening g' until stopped by the shoulder 98 with which such opening
is provided (see Figure 27). Both the feed lever and the pawl then move
together, the said pawl being at such time effectually prevented from rising by
its head g lying below the marginal portion of the slot 95. At the next
outward stroke of the feed lever the head g' will readily escape from the lateral
opening g', by the lateral movement of the pawl about its pivot 92 when the
nose meets the next cartridge or projection of the belt. The movement of the
pawl in this direction is limited by the inner wall g10 of the said slot g³ (Figure 26).
The aforesaid lateral projection 96 is made long enough to permit of the feed-
lever being thereby shifted by the gunner's fingers when desired. gll is a lateral
projection on the feed lever, which projection acts to guide the rims or flanges
of the cartridges into proper position for engagement with the cartridge carrier
as. the belt is fed step by step through the feed box. The aforesaid sliding
plate H has a depression 2 in order to permit the cartridge carrier to attain its
highest position without striking the said plate.
I is the crank-handle by which the mechanism can be operated by hand
(see Figures 1 and 8). It is capable of oscillating on a stud a projecting from
the side plate A and is connected by a bar i to a pin which is capable of sliding
in a long slot 10 in the said side plate A. The inner end of this pin lies in front
of a shoulder 10 (Figure 9) formed on the portion 8 of the action bar D, but
is not connected thereto. When the handle is actuated in the direction of the
arrow in Figure 1, this pin bears against the said shoulder and draws back the

page_text: action bar against the resistance of the aforesaid spring D7, thereby opening the
breech mechanism. When however the gun is working automatically the action
bar D moves rearwardly without shifting the said pin, by reason of the latter's
aforesaid loose connection therewith. Therefore when the gun is firing the
crank handle I remains stationary.
When it is desired to remove the breech block the hinged end piece A2 is
turned down about its pivot so as to uncover the rear end of the gun casing, the
crank handle I is then turned in the direction of the arrow in Figure 1 as far as
it will go, whereby the breech block will be almost, completely withdrawn from
the rear end of the gun. Then by a slight upward movement given to the breech
block by pulling it with the hand, it will readily become entirely detached from
the gun.
In order to permit of this upward movement of the breech block, the
action bar is cut away or grooved at 1 (see Figure 9) such grooved portion at
this time occupying a position beyond the gun framing owing to the action bar
being fully retracted by the said crank handle.
In cases where a water jacket is not employed we prefer to construct the barrel
of rectangular shape in cross section as shown in Figures 33 to 36 and to form it
with numerous transverse channels bb through which currents of air can flow
and cool the barrel. The said barrel may also be formed with external
grooves 6161 at the parts between the holes so as to increase the external surface
exposed to the atmosphere. Additional transverse channels 62 62 of less diameter
than the channels 66 may also be formed in the metal between the last mentioned
channels b as shown at Figures 35 and 36.
In the modified construction of the gun illustrated in Figures 37, the lock
and its strut are connected together by the same pin that carries the sears
and the lifting lever. In this case we may employ a firing pin formed in one
piece. We prefer however to construct the lock and its strut in the manner
set forth with reference to the gun previously described, that is to say with the
pivot pin carranged transversely across the longitudinal axis of the lock. In
other respects the gun illustrated by this figure is similar in construction to that
already described and therefore needs no further description.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is :-
1. In the mechanism of an automatic gun a breech block or lock provided
with a hinged or pivoted strut adapted to engage at the moment of firing with
fixed abutments substantially as described and for the purpose specified.
2. The combination with the aforesaid breech block or lock of a reciprocating
action bar having a rib or projection which acts upon inclined projections on the
hinged portion or strut of the lock substantially as described and for the purposes
specified.
3. The combination with the aforesaid breech block or lock and action bar, of
a lifting lever for elevating the cartridge carrier to its full extent just prior
to the completion of the upward movement of the strut substantially as described.
4. The peculiarly constructed action bar substantially as described with reference
to Figure 9 for the purpose specified.
5. The combination with the aforesaid breech block or lock of the jointed firing
pin substantially as described for the purposes specified.
6. A. reciprocating breech block or lock constructed and operating substantially
as described with reference to Figures 13 to 18 for the purposes specified.
7. The hinged rear extension piece provided with the trigger locking device
substantially as and for the purpose specified.
8. The cartridge-belt feed-lever operated by a sliding cam-plate which is con-
nected with the said lever and the breech block substantially as described with
reference to Figures 2, 28 and 29 for the purpose specified.
9. A cartridge-belt feed-lever and spring pawl, constructed and operating sub-
stantially as described with reference to Figures 22 to 27 for the purposes specified,

page_text: 10. The combination, with the action bar, of an external crank handle con-
nected with the action bar substantially as described and for the purpose specified.
11. The combination with the fixed or stationary barrel of parts comprising a
gas cylinder communicating with a chamber at the muzzle, a piston connected
with the action bar by a rod surrounded by a spring, and an outer casing for
the spring, substantially as described with reference to Figures 2 and for
the purpose specified.
12. A gun barrel formed with transverse air channels substantially as and for
the purpose specified.
13. An automatic gun having its parts constructed arranged and operating
substantially as described with reference to either of the constructions illustrated
by the accompanying drawings.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicants.