Hitherto we have been dealing with weapons worked by hand-power applied
to a lever or winch-handle, the motion of this lever being translated by
suitable mechanism into those by which the cartridges are loaded, fired,
extracted and ejected--the cycle continuing as long as the lever is
worked and there are cartridges in the "hoppers" which feed the gun. In
the modern "automatic" machine-gun, moreover, the loading, firing,
extracting and ejecting are all performed automatically by the gun
itself, either by the recoil of its barrel, or by a small portion of the
gases of explosion being allowed to escape through a minute hole in the
barrel near the muzzle. The following details of the British Maxim,
Hotchkiss and Colt types are reproduced from the article "Machine-guns,"
_Ency. Brit._ 10th ed.
The idea of using the recoil, or a portion of the gases of explosion,
for the working of the breech mechanism is by no means new, the latter
system having been proposed and patented (certainly in a very crude and
probably unworkable form) by (Sir) Henry Bessemer in 1854; but whatever
might be discovered by a search in old patent and other records or in
museums, there can be no doubt that (Sir) Hiram S. Maxim was the first
to produce a finished automatic gun of practical value. His patents in
connexion with this particular class of weapon date back to 1884, and
his gun on the recoil system was, after extensive trials, adopted into
the British army in 1889 and into the navy in 1892. It is very possible
that Bessemer's idea did not bear fruit earlier because the fouling left
by the old forms of "black" or smoky powders was apt to clog the moving
parts and to choke any small port. With modern smokeless powders this
difficulty does not arise.
[Illustration: FIG. 6.--Maxim Gun on Wheeled Carriage (1900).]
[Illustration: FIGS. 7 and 8.--Mechanism of Maxim Gun.]
Maxim Gun.
The Maxim gun,[6] as will be seen from figs. 7 and 8, consists of two
parts, the barrel casing (a) and breech casing (d), secured firmly
together. The former (a), which is cylindrical in form, contains the
barrel (b), and the water surrounding it to keep down the very high
temperature attained by rapid fire, and the steam tube (c), which by
the action of a sliding valve allows of the escape of steam but not of
water. The barrel has asbestos packings at its front and rear bearings
in the casing, which allow of its sliding in recoil without the escape
of water. The breech casing (d) is a rectangular oblong box, and
contains the lock and firing mechanism. At its rear end it has handles
(e) by which the gun is directed, and the thumb-piece (m) by which the
trigger is actuated. Its top is closed by a lid, hinged at (i). At its
front is a recess holding the feed-block (f) through which the belt of
cartridges (g) is fed to the gun.
Attached to the rear of the barrel (b) on either side are two side
plates (h), between which in guides O works the aggregation of parts
D, F, J, K, L, P, T and V, which constitute the lock, and (in
bearings) the crank axle E, crank E', and connecting rod I (see figs.
7 to 11).
The connecting rod I joins the lock and crank, being attached to the
side levers J of the former by means of the interrupted screw U; the
latter enables the lock to be detached and removed.
The crank axle E extends through both sides of the breech casing (d),
slots (k, fig. 7), allowing it a longitudinal movement of about an
inch. To its left-hand end, outside the breech casing, is attached the
fusee chain Y of the recoil spring X (see dotted lines in fig. 7), and
to its right-hand end a bell trunk lever, B B'; the arm B, which
terminates in a knob, being turned by the crank handle, the arm B'
working against the buffer stop C.
In figs. 8, 9 and 11 the breech is shown closed, and it will be
noticed that the crank pin I' is _above_ the straight line joining the
axis of the barrel, the striker T, and the crank axle E. As the crank
is prevented from further movement _upwards_ by the crank handle B
taking against the check-lever G (fig. 7), it is clear that the
pressure on discharge of the cartridge cannot cause the crank axle to
rotate, and so open the breech as shown in figs. 10 and 12.
The withdrawal of the lock and opening of the breech are effected as
follows: The _total_ travel in recoil of the barrel is about one inch,
but on discharge the barrel, the side plates and lock all recoil
_together_ for about a quarter of an inch without any disturbance of
the locking as explained above, and by the time this short travel is
completed the _bullet has left the muzzle_. The arm B' of the crank
handle then engages the buffer stop C and causes the crank axle E to
rotate and the crank E' to fall and so draw back the lock from, and
open, the breech. At the same time the fusee chain Y is wound up round
the left-hand end of the crank axle E and the spring X extended. In
the meantime the knob of the buffer handle B swings over, and just as
the lock reaches its rearmost position (as in figs. 10 and 12) strikes
the flat buffer spring H, and, rebounding, assists the crank in
revolving in the reverse direction; the spring X also contracts, and,
unwinding the fusee chain, draws back the lock again and closes the
breech, a fresh cartridge having been placed in the barrel as
explained below.
The gun is fired by means of the trigger F, which is actuated by the
projection (l) on the trigger bar (S), the latter being drawn back
when the button (m) on the push lever (n) is pressed forwards. If,
therefore, the button he kept permanently pressed, the projection (l)
will always lie in the path of the trigger F just as the lock reaches
its forward position and the breech is closed, and the gun will fire
automatically, and continue to do so as long as there are cartridges
in the belt.
The loading, extraction and ejection of the cartridges are effected as
follows: The left-hand side-plate is extended forwards a little beyond
the breech, and communicates the reciprocating motion of the barrel to
a lever on the feed-block, which causes the cartridges in the belt to
be fed forward one by one by a "step-by-step" pawl action, the
cartridge which is next to be taken from the belt being arrested
exactly above the breech, the ejector-tube Q being below in the same
vertical plane.
The extractor D (see figs. 9 to 12) which performs the operations of
inserting, extracting and ejecting the cartridges, travels vertically
in guides on the face of the lock. Projecting outwards from each side
of its top are horns N (figs. 9 and 10). These travel round the edges
of the cams M (fig. 8) situated on each side of the breech casing, and
in conjunction with the spring W (fig. 8), compel the top of the
extractor to take the path shown by the dotted lines and arrows in
figs. 9 to 12.
[Illustration: FIG. 9.--Maxim Gun Mechanism.]
The extractor (figs. 11 and 12) is recessed to take a movable plate
(u) termed a "gib," behind which is a spring (v). In the face of the
gib is a recess (w) into which the base of a cartridge can just enter.
On either side of the gib the face of the extractor has undercut
flanges, open at the top and bottom, between which the base of a
cartridge can fit the rim, being held in the undercuts (figs. 9 and
10).
It is clear from this arrangement that the base of the cartridge
having been introduced between the flanges at the top of the
extractor, can be pushed down, the spring (v) yielding, till arrested
at the recess (w); and, as the lower edges of this recess are slightly
sloped, further pressure will make it leave the recess (w) and slide
over the face of the gib, leave it, and take up a position in front of
the hole for the point of the striker (x), being now only prevented
from slipping out of the extractor by the extractor spring (y). If
this last be clear of the extractor stop (z) it will yield to pressure
and the cartridge will be free. This is the action in the gun except
that the cartridge is held firm and the extractor pushed against it.
In fig. 10 the extractor holds a cartridge (r) and a fired case (q)
ready to be pushed into the empty breech and ejector-tube Q
respectively. In the latter there is already a fired case (p), which
will be driven by the fired case (q) beyond the ejector spring R. As
soon as the lock reaches the face of the breech, the cartridge (r) and
case (q) are deposited in the breech and ejector-tube respectively,
and the extractor D _rises_ under the action of the levers L and J,
slides, as already explained, by the bases of the cartridges (r) and
case (q), and then over the base of the cartridge (s) in the belt (g).
Assuming the push-lever (n) to be pressed, the gun fires immediately
this has occurred, and the bullet of the cartridge (r) is expelled.
The position is now that shown in fig. 9. The barrel now recoils and
the lock is withdrawn, taking with it the fresh cartridge (s) from the
belt and the now fired case (r). The extractor travels horizontally
for a time and then drops (as shown by the dotted line and arrows),
assuming the position shown in fig. 12, which is exactly similar to
that in fig. 10 but with different cartridges; continuing the action,
the position shown in fig. 11 is arrived at. It will thus be seen that
each cartridge makes two complete journeys with the extractor; the
first as a live cartridge from the belt to the breech, the second from
the breech to the ejector-tube, the forward journey being always on a
lower level than that of the backward one. The sections in figs. 11
and 12 clearly show the cocking and firing mechanism and the safety
arrangement. The lock is cocked, after firing, by the arm of the
"tumbler" K, being pressed down by the side lever J as it swings down
when following the crank E'. Safety against firing before the breech
is closed is provided by the projection on the safety lever V, which
does not clear the striker T until lifted by the side lever J at the
top of its travel, that is, when the crank E' has passed the axial
line as already explained.
[Illustration: FIG. 10.--Maxim Gun Mechanism.]
The lock in its rearmost position is kept in place by the block Z on
the under side of the cover of the breech casing. When in this
position it is clear of the guides O on the side-plates, and if the
cover be opened it can be turned up, unscrewed by a turn through an
eighth of a circle (the screw-thread U being interrupted in four
places) and removed. To prepare the gun for firing, the crank handle
is pushed over by hand to the buffer-spring, thus withdrawing the
extractor, and held in this position; the tongue on the end of a
filled belt is then pushed through the feed-block from the left and
pulled as far as it will go from the opposite side. This places a
cartridge above the breech ready to be seized by the extractor. The
crank handle is now released and the lock flies forwards. The crank
handle is now again pushed over and let go, and the first cartridge
thus taken from the belt and placed in the breech. The gun is ready to
fire.
To remove a partially filled belt, the crank handle must be pushed
over, thus freeing the extractor from the belt, and the latter
withdrawn after pressing a spring catch under the feed block which
releases the pawls. The gun now has _two_ live cartridges in it--both
in the extractor. Letting go the crank handle, one of them is
deposited in the ejector-tube, and again pushing over and letting go
the crank handle does the same with the second.
[Illustration: FIG. 11.--Maxim Gun Mechanism.]
Fig. 13 shows the feed-block and the cartridge belts. The greatest
number usually carried in a belt is 250.
The gun is sighted to 2,500 yds. and has a folding tangent sight as
shown. Its weight varies from 50 to 60 lb., and it can fire about 450
rounds per minute.
[The diagrams have been made from drawings, by permission of Messrs.
Vickers, Sons & Maxim.]
Hotchkiss Gun.
The Hotchkiss gun, figs. 14 to 16, which has been adopted by the
French army and navy and elsewhere, depends for its action on the use
of a small portion of the gases of the cartridge itself. The barrel A
is firmly attached to the receiver or frame B, the latter containing
the breech and firing mechanism. Under the barrel A, and communicating
with it by a port (c) near the muzzle is a cylinder or tube C. When
the gun is fired, and the bullet has passed the port (c), a portion of
the gases of explosion passes into the cylinder C and drives back the
piston F contained in it, a lug on the under part of the piston
compressing the spring M, the latter, when the trigger N is pulled,
driving back the piston again. The reciprocating motion of the piston
performs all the processes of loading and firing the gun, and the
action is continuous as long as the trigger is kept pressed back.
The piston F, enlarged and suitably shaped at the rear, actuates the
breech-block H and firing pin or striker J; and, by suitable cam
grooves (f) at about the centre of its length, works the larger
feed-wheel U of the feed-box S; the smaller wheel U on the same axis
in turn imparting a step-by-step motion to the metal feed-strips, each
containing 30 cartridges, so that fresh cartridges are placed one by
one before the face of the breech block ready to be pushed into the
breech when the fired cartridge has been extracted and ejected.
On the under surface of the piston F, in rear, is a recess or sear (f)
in which the nose of the trigger N engages, holding back the piston
when it has been driven back by the gases. As already stated, a lug on
the under surface just in rear of the cam (f) engages with the front
of the mainspring.
[Illustration: FIG. 12.--Maxim Gun Mechanism.]
[Illustration: FIG. 13.--Maxim Feed-block.]
Taking first the position shown in fig. 15 with the breech closed and
locked and the cartridge fired, it will be seen that the breech is
locked by the _upper_ cam (_f_'), on the end of the piston, F, having
caused the movable locking-dog (h) to fall and bear against the recoil
blocks Z (see fig. 14 also) on the walls of the _receiver_ or frame B.
Consequently the breech is not unlocked until the piston has moved
sufficiently to the rear for the _lower_ cam (_f_') to lift the
locking-dog (h) clear of the recoil blocks Z. As the piston F is not
actuated by the gases until the bullet has passed the port (c), and
then has to move a short distance before the locking-dog is raised,
the bullet is clear of the muzzle _before_ the breech is unlocked.
As the piston continues to recoil it draws back the striker J and then
the breech-block H, and is then caught and retained by the engagement
of the sear (f) with the trigger N, and the position assumed is that
shown in fig. 14.
[Illustration: FIGS. 14, 15, 16.--Hotchkiss Gun Mechanism.]
From the head or nose-piece I of the breech-block projects the claw K
of a spring extractor which, as the cartridge is pushed home by the
breech-block, seizes it, extracting the fired case when the
breech-block is withdrawn. Ejection of the fired case is effected by
means of the ejector L (fig. 16) which catches against the base of the
case, on the opposite side to the extractor claw, and so throws it
sideways through the oblong-pointed opening in the receiver just in
rear of the breech (see fig. 14).
The platform on the top of the feed-box through which the teeth of the
smaller feed-wheel U project, and on which the feed-strips rest, lies
_below_ the axial line of the breech-block H, so that the face or
nose-piece I of the latter only engages a _portion_ of the base of the
cartridge in the feed-strip as it pushes the cartridge into the
breech, the bullet of the cartridge being guided into the breech by
the incline at the opening of the latter. This point should be
specially noted, the object of the arrangement being to enable the
under surface of the breech-block to clear the clips which hold the
cartridges in the feed-strips. The cartridge therefore, being
extracted in the line of the axis of the block, is ejected through an
opening _above_ its plane of entry in the feed-strip.
Returning to the position shown in fig. 16, if the trigger be pulled,
the compressed spring M reacts and drives the piston forwards,
carrying the breech-block with it, the latter in turn driving a
cartridge in front of it out of the feed-strip. When the block and
cartridge are home, _and not till then_, the piston completes its
travel, the upper cam (_f_') locking the dog (h), and the firing-pin
protrudes and fires the cartridge. Anything, therefore, which prevents
the breech-block from being home against the breech, or the
locking-dog from falling in front of the recoil blocks Z, renders
firing of the cartridge impossible. Clearly if the trigger be kept
depressed the action becomes automatic.
A special feature of this gun is the absence of a separate spring to
actuate the firing-pin; the recoil spring M performing this function,
in addition to that of driving the piston forwards.
The feed-strips have holes in them in which the teeth of the smaller
feed-wheel U engage. The engagement of this feed with the piston F can
be released by pulling out the feed arbor W, so that the strips can be
removed at any time.
When the last shot in a feed-strip has been fired a stop (V) holds the
piston and block ready for a fresh feed-strip to be inserted. As the
stop V acts quite independently of the trigger, this action takes
place even if the trigger be still depressed after the last cartridge
in a strip has been fired.
To cock the gun, when in the locked position, a cocking handle G is
provided. This has a long arm projecting to the front with a catch
which takes against the front of the lug on the under side of the
piston. To prepare the gun for action the gun is cocked, and a
feed-strip is pushed into the feed-block.
The pressure of the gas on the piston is regulated by the regulator
screw D, by means of which the space in the cylinder C in front of the
piston F can be reduced or increased.
A safety lock R is furnished, which is a "half round" pin which can be
turned so as to enter the semicircular slot just in front of the sear
(f), and so hold back the piston when in the cocked position.
Radiation of the heat, generated in the barrel by rapid fire, is
facilitated by the radiator (a), which consists of rings on the barrel
close to the breech, which offer an increased surface to the air.
The gun is sighted to 2000 yds., with the ordinary flap back-sight,
weighs about 53 lb., and can fire from 500 to 600 rounds per minute.
[The diagrams have been made from drawings, by permission of the
Hotchkiss Ordnance Company.]
Colt Gun.
The Colt automatic gun, which has been adopted by the American army
and navy, and was used by the British in S. Africa, depends for its
action, similarly to the Hotchkiss, on the escape of a small portion
of the gases of explosion through a port in the barrel a short
distance from the muzzle. Figs. 17 and 18 give a plan, and side
elevation with the left side plate removed, respectively. Into the
recess in the barrel (92) just below the port fits the piston (35),
capable of slight motion round the pivot (36), by which it is attached
to the gas lever (29). The latter is a bell-crank lever pivoted at
(34), its short arm being attached at (46) by a pivot to a long link
with a cross head, termed the retracting connexion (45). This link
extends from a point close to the figures (44), where the arms of the
cross head bear against the ends of two long spiral retracting
springs, (37) and (38), contained in two tubes, (39) and (40), which
are slotted for a few inches of their length to allow the cross head
to follow up and compress the springs. (Only (38) and (40) are shown,
(37) and (39) lying in the same plane of projection.)
When the gun fires, and the bullet has passed the port, the gases
drive the piston (35) and gas lever (29) downwards, and the momentum
imparted causes them to swing back round the pivot (36), as shown by
the dotted circle. The gas lever is brought up now by the bottom plate
(91); and the retracting springs, compressed by the cross head of the
long link (45) owing to the _forward_ motion of the short arm of the
gas lever, react and drive the gas lever into its forward position
again.
[Illustration: FIGS. 17 and 18.--Colt Automatic Gun Mechanism.]
The rotary movement of the gas lever is converted into a reciprocating
movement of the slide (86) by means of the gas lever connexion rod
(31) pivoted at (32) to the gas lever, and at (87) to the slide.
The slide (86) is a nearly flat bar, travelling in guides in the
receiver, extending from (14) to (87). It is slotted completely
through longitudinally for nearly the whole of its length, this slot
affording an opening through which work the cartridge extractor (82)
and carrier (21). At its rear end it engages by means of a pin (14) in
a cam slot (97) in the bottom rib of the bolt (13), and at (83) it
bears the pivot of the cartridge extractor (82). Its rear end is
enlarged below to form a cam lug (98), and on its right side are two
projections (95) and (96), which work the feed lever (66).
[Illustration: FIG. 19.--Colt Gun mounted.]
The feed wheel (61), over which passes the belt containing the
cartridges, is actuated by a pawl "step-by-step" gear by means of the
feed lever (66).
The carrier (21) is a long trip lever pivoted at (22), and provided
with a spring dog (23) pivoted at (24).
The bolt (13) is a cylinder with a guide rib extending from its under
surface. It is actuated by the slide by means of the pin (14) and cam
slot (97) as already stated, and is bored through to take the striker
or firing pin (18). The rear end of the latter projects slightly
beyond the rear face of the bolt, being retained in this position by
the spring (19). When this projecting end is pushed into the bolt, the
point protrudes from the front of the bolt and fires the cartridge.
The bolt, when the breech is locked, is held firm by two recoil blocks
on the receiver (not shown), as is explained later. At the front of
the bolt is an extractor (15) with a spring claw for extracting the
fired case. (This is of course quite distinct from the cartridge
extractor (82).) Ejection is effected by means of an ejector
projecting into the path of the fired case.
The firing of the gun is performed by the cylindrical hammer (6)
hollowed out in rear to contain the mainspring (7). When pushed back
and cocked as shown in fig. 18, it is held during a _portion_ of the
operations of the mechanism by two detents working independently of
each other--the sear (10) and the nose of the trigger (8). The former
is automatically released by a trip lever (not shown) as soon as the
breech is locked, leaving the hammer held by the trigger only. This is
the position shown in fig. 18. The necessity for the two detents is
explained later.
The hammer, when cocked, can also be permanently locked by the handle
lock (2) actuated by a thumb-piece on the outside of the receiver. The
air compressed in rear of the hammer, as the latter is driven back,
passes through the tube (99) to the breech; and a puff of air is
therefore blown through the barrel after every shot, clearing out
fouling and unconsumed powder, and assisting to an appreciable extent
to keep down the temperature of the barrel.
Taking the position shown in fig. 18, the hammer is only held back by
the trigger nose, the sear (10) having been released as stated above.
A belt of cartridges (not shown) has been placed on the feed-wheel,
and the cartridge next to be used after the one (not shown) now in the
breech has its rim (or base with rimless cartridges) just above the
hook on the extractor (82). If now the trigger be pulled, the hammer
flies forwards, strikes the protruding end of the firing pin, and the
cartridge fires; the gases cause the gas lever to swing round and
drive back the slide. The pin (14) working in the cam groove (97)
causes the rear of the bolt to _rise_ and clear itself from the recoil
blocks (not shown) on the receiver, and then to move rearwards
horizontally, driving the hammer back until the latter is caught and
held by the sear and trigger. In the meantime the extractor (82) has
pulled a cartridge from the belt, and, assisted by two spring
cartridge guides (80 and 81), of which only (80) is shown, deposits it
on the carrier (21); the projection (95) strikes the feed-lever (66),
and moves the feed mechanism so as to prepare to revolve the
feed-wheel and place a fresh cartridge ready for the next round; and
as the slide completes its travel backwards, the cam (98) strikes the
dog (23) and slightly depresses it (the spring (25) yielding), the
carrier and cartridge on it consequently rising a little and falling
again (this latter action is incidental only to the form of the parts,
and is not a necessity).
[Illustration: FIG. 20.--Hotchkiss Gun mounted.]
The retracting springs now react and pull the slide forwards; the cam
(98) strikes the dog (23), which, as the spring arrangement is of the
"non-return" class, does not yield but is depressed, and the front of
the carrier and the cartridge on it are therefore raised sharply, and
the latter placed in the path of the bolt. The bolt being now pulled
forwards, the cartridge is driven off the carrier into the breech, and
the bolt locked by the pin (14), causing the bolt to drop in front of
the recoil blocks; the carrier is pushed down flat by the advance of
the cam lug (98), the trip releases the sear (10), and the projection
(96) pushes back the feed lever, completing the action of feeding a
fresh cartridge forward. The position shown in fig. 17 is now resumed.
It is clear that were the trigger kept permanently pulled the gun
would fire immediately the bolt was locked and the sear (10)
depressed, and the action would become automatic.
The object of two detents, though now probably obvious, may here be
explained. The whole action of the gun depends upon the hammer after
it is pushed back by the bolt being _held_ back until the bolt has
gone completely forwards and locked the breech. If only the trigger
detent existed, and that were kept pressed down, the hammer, after
being pushed back by the bolt, would immediately _follow up_ the
latter, and might fire the cartridge prematurely, or fail to fire it
at all; hence the use of the sear in addition to the trigger.
To cock the lock, or work the mechanism by hand, the gas lever is
pulled round by the pin (30) provided for the purpose, and by this
means the gun is prepared for firing. A brass tongue on the end of the
belt is pushed through the opening above the feed-wheel and then
pulled from the other side of the gun as far as it will go. This
places a cartridge in front of the extractor, and if the gas lever be
now pulled right back and let go, this cartridge is placed in the
breech as already described, and the gun is ready for firing. If it be
desired to remove a belt from the feed, a button (68) is pressed and
the feed-wheel is then free to revolve backwards.
The gun is sighted with the ordinary rifle-pattern sights, up to 2000
yds. or more if required. It weighs about 40 lb., and can fire about
400 rounds per minute as usually adjusted, though this rate can be
increased. There is no means of altering the gas pressure in the field
as with the Hotchkiss.
[The diagrams have been made from drawings, by permission of the Colt
Arms Company.]
Comparing the principle of employing a recoiling barrel with that of
using a portion of the gas, the advantages of the former are that the
recoil is made to do useful work instead of straining the gun and
mounting in its absorption; the latter system, however, has undoubtedly
the advantage in simplicity of mechanism (the Hotchkiss is
extraordinarily simple in construction for an automatic gun), and in the
large margin of power for working the mechanism with certainty in all
conditions of exposure to climate, dust, and dirt. While inferior in
this respect, it is nevertheless the fact that the Maxim has proved
itself in the field even in savage warfare in the roughest country to be
a very efficient and powerful weapon.
The great difficulty which has to be met in all single-barrel machine
guns is the heating of the barrel. The 7½ pints of water in the
water-jacket of the Maxim gun are raised to boiling point by 600 rounds
of rapid fire--i.e. in about 1½ minutes--and if firing be continued,
about 1½ pints of water are evaporated for every 1000 rounds. Assuming
that the operation is continuous, the rate of waste of energy due to
heat expended on the water _alone_ is equivalent to about 20 horse-power
(294 foot tons per minute). The water-jacket acts well in keeping down
the temperature of the barrel; but apart from the complications entailed
by its use, the provision of water for this purpose is at times
exceedingly troublesome on service. In the Hotchkiss and Colt guns,
which have no water-jacket, an attempt is made to meet the heating, in
the one by the radiator, and in the other by a very heavy barrel.
[Illustration: FIG. 21.--Tripod mounting (Mark IV.), for British Maxim.]
One of the most modern types of gun is the Schwarzlose, which is
manufactured at Steyr in Austria, and was adopted by the Austrian army
in 1907. This weapon is remarkable for its simplicity. There are only 10
main working parts, and any of these can be replaced in a few seconds.
It is operated by the gases of the explosion, has a water-jacket that
allows 3000 rounds to be fired without refilling. The "life" of the
gun-barrel is stated to be 35,000 rounds without serious loss of
accuracy. The weight of the gun is 37.9 lb. It is a belt loader.
The Italian Perino gun, adopted in 1907, is a recoil-operated weapon,
and is loaded by a metal clip. The Skoda gun, some of which type are
used in Japan and China, is loaded by a hopper feed, and is
gas-operated. The Bergmann gun is a belt loader, but the belt passes
down a "gravity feed" an arrangement which saves a number of working
parts.
One defect common to all is that it is by no means easy to proportion
the fire to the target, as there are only two rates of fire, viz. rapid
automatic and slow single shots. To fire a single shot requires
practice, since the gun will fire some 7 shots in one _second_, and to
press the trigger and remove the finger or thumb instantly, and at the
same time be ready to traverse to a fresh target, requires considerable
skill. The result of these difficulties is that the target when struck
is often riddled with bullets when one would have sufficed. The aiming
of the gun, when rapid fire is taking place, may also be difficult even
on firmly fixed mountings, owing to vibration. The greater delicacy of
the modern machine gun has been alluded to above.[7] Nevertheless the
advantages of safety, steadiness and lightness which the automatic
weapon possesses, have ensured its victory over the older type of
weapon, and although the simple strong and well-tried Gatling still has
its advocates, every civilized army has adopted one or more of the
automatic types.