Czechoslovak-made ZGB-30
prototype machine gun in .303 caliber
Czechoslovak-made
ZGB-33 prototype machine gun in .303 caliber
Bren Mk.1 light machine gun,
right side
Bren Mk.1 light machine gun,
left side
Bren Mk.2 light
machine gun
Bren Mk.3 light machine gun
(note the short barrel)
Bren L4A4 light machine gun in 7,62x51 NATO caliber
BREN Mk.1
BREN Mk.3
BREN Mk.4
BREN L4A4
Caliber
7,7x57R (.303)
7,62x51 NATO
Weight, kg
10,04
8,76
8,69
8,68 (with bipod)
Overall length, mm
1156
1082
1090
1156
Barrel length, mm
635
565
565
635
Cyclic rate of fire, rounds per
minute
500
480
520
520
Feed and capacity
Magazines, box 30 rounds or pan
100 rounds
Box magazine, 30 rounds
Box magazine, 30 rounds
In the year of 1930 British army decided to organize
a large comparative trials for a new light machine gun, which included
weapons of both domestic and foreign origins. Those included: American
Browning Automatic Rifle in .303 caliber, French Darne LMG in same
caliber, British Vickers-Berthier LMG, Swiss KE-7 and Danish Madsen
LMG. The last entrant, which also was the only one chambered in
non-standard caliber (7,92x57 Mauser rather than .303 British) was the
Czechoslovak ZB-26 LMG. The ZB-26
was brought to attention of Small Arms Committee during the last
minutes before trials by the British Military Attaché in
Czechoslovakia. First round of trials resulted in ZB-26
coming the first, and Vickers-Berthier second. As the Darne LMG came
too late for these trials, it was included into the second stage of
trials, which included Vickers-Berthier and an improved Czechoslovak
ZGB-30 LMG in .303 British caliber. Final conclusion of the testing
commission was that “ZB gun is of such outstanding design, workmanship
and materials as to warrant further serious consideration”. During
1932, the test ZB gun was brought back to Brno for further
modifications, which eventually resulted in ZGB 32 light machine gun.
According to British requirements, this weapon had a 30-round magazine
(earlier prototypes had 20-round magazines) and receiver which could
recoil against a special buffer – a feature that significantly
decreased felt recoil of the gun. The ZGB 32 was tested, and this
resulted in more requirements from the British side, including lower
rate of fire and slightly abbreviated barrel. The modified ZGB 33 LMG
were tested in January 1934 with great success, and final trials
between ZGB 34 (next improved model) and a heavy-barreled
Vickers-Berthier were held in August 1934. The net result of this 50
000-round endurance test was the recommendation of ZGB 34 for adoption
by British army. The licensing arrangements with Československa
Zbrojevka Brno permitted the manufacture of a new gun, designated as
BREN (for Brno and Enfield), at Royal Small Arms factory in Enfield
Lock. Production preparations were commenced late in 1934, and by early
1935 all manufacturing documentation was converted from metric to inch
scales. First Bren Mark 1 light machine gun left the Enfield factory in
September 1937. During the WW2 period, Bren guns were also made in
Canada by John Inglis Co and in Australia by Lithgow Small Arms
factory. Throught the WW2 Bren machine guns proved to be highly
effective, reliable and very accurate weapons. During the war, the Bren
guns were gradually simplified and lightened, resulting is a series of
Marks, from original Mark 1 and up to Mark 4. At the same time, Inglis
Co in Canada produced a number of Bren guns in 7,92 Mauser caliber for
China. When the UK has jointed the NATO in 1954, it solved the
problem of the light machine gun in new standard caliber (7,62x51 NATO)
by simple adaption of the Bren to the new cartridge. This was
relatively easy effort, because 7,62NATO round shares same base
dimensions with 7,92x57 Mauser round, which was used in Canadian-made
Chinese contracy Bren guns. Therefore, early conversions to the NATo
standard included "Chinese contract" bolts, new barrels, magazine
adaptors and new magazines. These "NATO standard" Bren guns received
official index L4 and also went through a number of modifications. Bren
L4 light machine guns served until 1980s, and were quite popular among
the British troops.
The BREN is a gas-operated, air cooled,
selectively fired machine gun. It has a quick-detachable barrel and
fires from an open bolt. Under intense fire (about 4 magazines / 120
rounds per minute) the barrel should be replaced every 300
rounds. The action of gun is powered by a long-stroke gas piston,
located below the barrel. The gas block is mounted on the thin tubular
sleeve which goes around the muzzle end of the barrel and forms the
conical flash hider at the front. Gas block has a manual gas regulator
with four settings. The action is locked by tipping the rear of the
bolt (breechblock) upwards, and into a locking recess in the
receiver. The return spring is located in the butt of the weapon,
and is connected to the bolt carrier / gas piston via a long rod;
additionally, there is a short spring buffer located below the return
spring at the juncture of the receiver and butt, which acts against the
whole receiver which is permitted to recoil short distance on the long
rails of the trigger housing / butt group. This system significantly
decreases felt recoil during fire. The charging handle is located at
the right side of receiver and does not reciprocate when the gun is
fired. On later marks of the gun it is of folding type. The
ammunition feed is from top-mounted box magazines. These are made from
sheet steel and hold 30 rounds in a two-row configuration (although in
the field soldiers preferred to load only 27-28 rounds to reduce strain
on the magazine spring and thus ensure reliability of the feed under
harsh conditions). The Mark 1 BREN guns were also provided with
spring-powered flat pan magazines, which held 100 rounds. Such
magazines were issued mostly for anti-aircraft applications, and were
dropped from latter Marks because of complexity and cost. The magazine
housing has a sliding dust cover which is slid forward to load the gun.
Spent cartridges are ejected downwards. The ejection port is normally
closed with its own dust cover which opens automatically once the
trigger is pressed. The trigger unit permits both single shots and
automatic fire, selectable through a safety / fire mode selector lever
situated at the left side of the pistol grip. The gun fires from an
open bolt and the spring-loaded firing pin is operated by a projection
on the bolt carrier, once the bolt is fully in battery and locked. Because
of the overhead magazine, the sight line is offset to the left, and the
front sight is mounted on a base which protrudes upward and to the left
from the gas block. Standard furniture consists of an integral
folding bipod, which is attached to the gas cylinder tube, wooden
pistol grip and butt with a spring-buffered buttplate and a folding
shoulder rest plate. Mark 1 BREN guns were also equipped with folding
grip below the butt. Despite the fact that the BREN, like its
predecessor ZB-26 was mainly intended for
the light machine gun role, it was also offered with a sustained-fire
tripod, and provided with a sufficient supply of full magazines and
spare barrels it could serve (to some extent) as a medium machine gun.
The same tripod was also adaptable for the AA role. Dual gun mounts
were used for anti-aircraft role and on certain land vehicles, used for
Commando “hit-and-run” missions during WW2.
Modifications: ZGB: Czechoslovak-made BREN-type guns, produced for export during early post-WW2 period in .303 caliber BREN Mk.1: original version with radial type sight, and additional grip under the butt (not present on latter marks) BREN Mk.1(M):
Canadian-made version, with simplified non-telescoping bipod legs and
simplified butt without shoulder rest and buttplate buffer; also was
made in 7,92x57 calibre for China BREN Mk.2: Simplified war-time version with simplified rear sight BREN Mk.3: Lightened version of the Mk.2, with barrel shortened by 70mm (2 ¾ inch) BREN Mk.4: Minor variation of previous mark, with different butt shape BREN L4A1:
Bren Mk.3 guns converted to 7,62x51 NATO ammunition using Canadian-made
7,92x57 bolts (Chinese contract) and new barrels and magazines; each
gun was issued with two barrels BREN L4A2: Same as L4A1 but with lighter bipod BREN L4A3: Bren Mk.2 converted to 7,62x51 NATO the same way as L4A1 BREN L4A4: Similar to L4A1 but barrel is chrome-lined; only one barrel was issued per gun (no spare barrels at unit level) BREN L4A5: same as L4A3 but with chrome-lined barrels. Issue was limited to British Navy BREN L4A6: L4A1 re-issued with chrome-lined barrel BREN L4A7: Conversion of Bren Mk.1 to 7,62x51, proposed for Indian army; not produced BREN L4A8: Not produced BREN L4A9: L4A4 modified with addition of the sight bracket for AA or Night/IR sighting equipment