It is well known that the Bren Light Machine Gun was developed from the Czech ZB26 designed by Vaclac Holek of Zbrojovka Brno.  The British Government also adopted and modified another Holek-designed air-cooled, gas-operated machine gun, the ZB53, and a derivative of heavier calibre, the ZB60.  Both models were belt fed.

As the ZB53 was acquired primarily for mounting in tanks and armoured cars, and would therefore be a relatively limited issue, the British departed from their prudent policy of chambering all light and medium machine guns for one cartridge only – the .303 rimmed.  The Czechs designed the ZB53 around the German 7.92 x 57 mm rimless cartridge and the British avoided the problems associated with a change of calibre, particularly from a rimless to a rimmed case, by producing their versions in the same calibre.  The ZB60 was chambered for the 15 x 104 mm cartridge and this also was retained by the British.

Both British models were produced by Birmingham Small Arms Limited (BSA) and were given the designation Besa.  Production of the 7.92 mm model commenced in 1939 and BSA manufactured 59,322 of the model during the 1939-1945 War.  The 15 mm Besa was brought into service in June 1940 and was substantially an enlargement of the earlier weapon.

7.92 mm Besa.

While the Besa was gas-operated, it also had a recoiling barrel, giving what was termed a ‘differential system’.  In essence, the cartridge was chambered and discharged while the operating mechanism was still moving forward in counter-recoil.  The recoil produced by the fired cartridge had then to arrest the inertia of the forward-moving bolt before reversing the movement.  This action aided in buffing the bolt and it is said that the imposed change of direction absorbed much of the recoil and contributed to a reduction of stress on the weapon and its mounting.  Whether or not this enhanced the weapon’s performance, British troops had a particularly high opinion of the Besa’s accuracy.

The Besa 7.92 mm was put into service in seven different versions.  The Mark I and Mark II were both introduced in June 1940, with the Mark I being declared obsolescent on the same day.  The Mark II varied from the Mark I in minor details, with most of the changes being made to facilitate production.  Both marks were designed for automatic fire only and had an accelerator that enabled variation of the rate of fire.  With the accelerator set to L (low), the cyclic rate of fire was 450-550 rounds per minute (rpm).  On H (high), the cyclic rate of fire was increased to 750-850 rpm.  The lower rate of fire was for normal use while the higher rate provided greater power in repelling attacks or in other pressing circumstances.

The Mark II*, Mark III and Mark III* were all introduced in August 1943.  The Mark II* was a transitional model between the Mark II and the Mark III and, although some parts were simplified, there was complete interchangeability of Mark II and Mark II* parts.  Mark III parts would not, however, interchange with earlier marks.  The Mark III and Mark III* were further simplified and had the accelerator removed.  The only difference between the Mark III and the Mark III* was that the Mark III had the rate of fire set at 750-850 rpm while he Mark III* was set at 450-550 rpm.  All Mark III models were later converted to Mark III*.

The Mark III/2 introduced in 1952 modified the Mark III* with a new bracket and body cover.  Introduced in 1954, the Mark III/3 had a new design of barrel and sleeve and larger gas vents, to facilitate the use of belts of mixed types of ammunition.  Some Mark III/2 guns were converted to Mark III/3 but there was no manufacture of new Mark III/3 guns.

Besas mounted in armoured fighting vehicles (AFVs) used telescopic sights but the Czechs also used the ZB35 as a tripod mounted medium machine gun (MMG) with iron sights.  In 1937 the British gave some consideration to introducing the Besa as a replacement for the Vickers MMG but did not proceed due to the difficulty of converting to the .303 inch cartridge.  While an exception was made for tank machine guns, the British were not prepared to introduce another cartridge for extensive infantry use.

The earlier marks of the Besa 7.92 mm were made obsolete in 1951 but the Mark III/2 and Mark III/3 remained in service to the late 1960s.

15 mm Besa

In substance, the Besa 15 mm heavy machine gun was an enlargement of the 7.92 mm gun.  It did, however, differ in that it could be fired on repetition (single shot) and had a cyclic rate of fire of 450 rpm.  The Besa 15 mm was produced only in one mark and an attempt to convert the weapon to 20 mm calibre, to permit the use of the Hispano-Suiza 20 mm cartridge, was abandoned.  As did the Besa 7.92 mm, the 15 mm gun employed an unusual method of cocking.  Pushing forward the trigger guard body engaged the operating mechanism which was then brought back to the firing position when the trigger guard body was withdrawn to the rear.  A cocking catch locked the trigger guard in the firing position.

At the time, the Besa 15 mm was considered to be too large and heavy for the intended application.  The subsequent trend has, however, been to larger automatic cannon in armoured cars, armoured personnel carriers (APCs) and other light armoured vehicles – for example the Rarden 30 mm and the Hughes chain guns in 25 mm and 30 mm.

The Besa 15 mm was made obsolescent in 1944 and became obsolete in 1949.

While the British appear to have lagged in initiative in the design of machine guns, they exercised excellent judgement in the selection of foreign automatic weapons for issue to their armed forces. Certainly, those of Czech design gave superior performance in British service.

TECHNICAL DETAILS

BIBLIOGRAPHY

Ezell, E.C., Small Arms of the World: a basic manual of small arms, 11th Edition, Harrisburg, Stackpole Books, 1997.

Harding, D., Weapons: an international encyclopedia from 5000BC to 2000AD, London, Book Club Associates, 1980.

Hogg, I.V., The Illustrated Encyclopedia of Firearms, London, New Burlington Books, 1987.

Hogg, I.V. & R. Adam, Jane’s Guns Recognition Guide, Glasgow, Harper Collins Publishers, 1996.

Hogg, I.V. & J. Weeks, Military Small Arms of the 20th Century: A Comprehensive Illustrated Encyclopedia of the World’s Small-Calibre Small Arms, 6th Edition, London, Arms and Armour Press, 1991.

Myatt, F., Modern Small Arms, London, Salamander Books, 1978.

Smith, W.H.B., Small Arms of the World: The Basic Manual of Military Small Arms, 4th Edition, Harrisburg, Military Service Publishing Company, 1953.