The Royal Ordnance L7, officially designated Gun, 105 mm, Tank, L7, is the basic model of the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...
's most successful
tank gun. The L7 is a
105 mm L/52 rifled design by the
Royal Ordnance Factories intended for use in
armoured fighting vehicle
An armoured fighting vehicle (AFV) is an armed combat vehicle protected by armour, generally combining operational mobility with offensive and defensive capabilities. AFVs can be wheeled or tracked. Examples of AFVs are tanks, armoured ca ...
s, replacing the earlier
QF 20-pounder (84 mm) tank gun mounted on the
Centurion tank. The successful L7 gun has been fitted on many armoured vehicles including the British Centurion (starting from the Mk. 5/2 variant), the German
Leopard 1 and several variants of the US MBTs
M48 Patton and
M60 in an altered design, the
M68.
The L7 is a popular weapon and continued in use even after it was superseded by the
L11 series 120 mm rifled tank gun, for some Centurion tanks operating as Artillery Forward Observation and
Armoured Vehicle, Royal Engineers (AVRE) vehicles. The L7, and adaptations of it, can be found as standard or retrofitted equipment on a wide variety of tanks developed during the Cold War.
History
Both the United Kingdom and the United States had been developing projects for large calibered guns during WWII in order to compete with increasingly heavily armored German tanks, and later for
Cold War Soviet tanks. The US developed several heavy tank designs during this period, notable were the US
105 mm Gun Motor Carriage T95 (also known as "Super Heavy Tank T28") as well as the
QF 32-pounder mounted on the British A39
Tortoise heavy assault tank.
The US foresaw difficulties in engagements against the Soviet
IS-3 and 4 with its M47 Patton. This led to the introduction of the
M103, a
heavy tank designed to counter
Soviet heavy tanks. It mounted an extremely powerful 120 mm cannon but the ammunition was so large that it required two loaders, one for the shell and another for the separate propellant charge. Of the 300 M103s built, most went to the Marines. The UK came to the same conclusions and developed their own heavy tank, the
Conqueror, which mounted the L1 120 mm gun.
United Kingdom
During the
Hungarian Revolution of 1956, a Soviet T-54A medium tank was driven onto the grounds of the
British embassy in
Budapest
Budapest (, ; ) is the capital and most populous city of Hungary. It is the ninth-largest city in the European Union by population within city limits and the second-largest city on the Danube river; the city has an estimated population ...
by the Hungarians in November. After a brief examination of this tank's armour and 100 mm gun, British officials decided that the 20-pounder was apparently incapable of defeating its frontal armour. This meant the most common British tanks were no longer able to effectively deal with Soviet medium tank designs, let alone their heavy tanks.
These events spurred the United Kingdom to employ a new high-velocity tank gun in 1958, the Royal Ordnance L7 to keep existing Centurion tanks viable against this new Soviet tank design. While the United States began design development of the
XM60 tank in 1957 and began user trials of the weapon in 1958. The L7 was specifically designed to fit into the turret mountings of the 20 pounder. This would enable the
Centurion tanks to be up-gunned with minimum modifications; hence, the fleet could be upgraded in a shorter time and at a lower cost. The first production tank to integrate the L7 was a single up-armoured Centurion Mark 7 in 1958 which was to prove the future viability of up-armouring and up-gunning the Centurion. From 1959 onwards newly built Centurions incorporated the L7 at production.
United States
The main gun for the M60 tank series was chosen after a comparative firing test of six different guns carried out on the Aberdeen Proving Ground in 1958. The factors evaluated were accuracy, the lethality of a hit, rate of fire, and penetration performance. Based on these tests, the 105 mm T254E1 was selected, modified to the T254E2 and standardized as the Cannon, 105-MM Gun, M68. The T254E2/M68 used a vertical sliding breechblock instead of the T254E1's horizontal breechblock. Until American-made barrels could be obtained with comparable accuracy, British X15/L52 barrels mounting a concentric bore evacuator on the barrel were to be used. US built XM24/L52 barrels (length 218.5 inches)
fitted with an eccentric bore evacuator were used for the M60-series starting in June 1959 but retained interchangeability with the British X15/L52 barrel. All of the US guns and XM24 barrels were produced at the
Watervliet Arsenal, NY and the gun mounts (M116 for the M60 and M140 for the M60A1/A3) manufactured at the
Rock Island Arsenal, IL.
US M68 guns were fitted with an eccentric bore evacuator instead of a concentric model in order to provide more clearance over the rear deck of the tank.
[TM 9-2350-253-20-2 Organizational Maintenance Manual--Tank, Combat, Full Tracked: 105-mm Gun, M60A3 (2350-00-148-6548) and (2350-01-061-2306) TTS Turret. Washington, D.C.: Dept. of the Army, 15 April 1980] The original variant of the M60 tank was equipped with the M68 gun using the M116 mount. Additionally, many M48A3s armed with a 90mm gun that were in NG-CONUS service with the
Army National Guard
The Army National Guard (ARNG), in conjunction with the Air National Guard, is an organized Militia (United States), militia force and a Reserve components of the United States Armed Forces, federal military reserve force of the United States A ...
were retrofitted with the M68 gun and re-designated as the M48A5. This was done to maintain training levels of Guard units as well as using a commonality in ammunition amongst tanks.
The M60A1 and A3 variants of the
M60 series and earliest pre-production XM1 prototypes of the
M1 Abrams
The M1 Abrams is a third-generation American main battle tank designed by Chrysler Defense (now General Dynamics Land Systems) and named for General Creighton Abrams. Conceived for modern armored ground warfare and now one of the heaviest ta ...
tanks are armed with the M68E1 variant of the gun. The M68E1 gun shares the same firing characteristics as the M68. It featured several design improvements including an updated gun hydraulic configuration, a stabilization upgrade for the gun, a gun elevation kill switch for the loader, improved ballistic drive and other component refinements. They were fitted with thermal sleeves on the barrels starting in 1973.
During the mid 1970s it was becoming clear that the latest generation of composite based armor was impervious to tungsten carbide penetrators.
Work was performed at the
Department of Energy's
Pacific Northwest National Laboratory
Pacific Northwest National Laboratory (PNNL) is one of the United States Department of Energy national laboratories, managed by the Department of Energy's (DOE) Office of Science. The main campus of the laboratory is in Richland, Washington.
O ...
to engineer development of depleted uranium as a penetrator material for future ammunition while the Armament Research and Development Command (ARRADCOM) was improving the performance of the 105mm M774 cartridge.
The improved M833 round starting in 1983, also using a depleted uranium penetrator to keep the M68E1 gun viable against this improved armor. In 1975 an updated version of the gun, the T254E3 was designed, focusing on the use of chrome plating to improve accuracy. It was used to evaluate improvements to the gun's performance using discarding sabot ammunition. Two guns were built and underwent firing trials at Aberdeen and technical evaluations at the Watervliet Arsenal. Based on the results of these tests the shortcomings of plated bores and gun tubes were found to outweigh any advantage they might offer and the program dropped by May 1976.
In January 1978, a program was initiated
to develop an enhanced version of the 105mm gun, the M68A1 as a possible alternate weapon for the M1 Abrams.
[CANNON, 105MM GUN: M68A1E2 MIL-C-45504A Rev. D Jan 1987 , Military and Government Specs & Standards (Naval Publications and Form Center) (NPFC)] had a higher chamber pressure, reinforced breech
allowing the use of high-energy propellants.
Although the
M256 120mm smoothbore gun was chosen to be the main weapon of the M1 Abrams in 1979, the ammunition for the gun was still not fully developed, thus delaying its fielding until 1984.
The early production versions of the M1 Abrams (M1 & IPM1) were armed with the M68A1 for two reasons. First was due to the large number of M60 Patton tanks with the M68E1 gun still in widespread US service in the 1980s and a large on-hand stockpile of 105mm munitions. Fitting the M1 with the M68A1 gun was viewed as an economical and practical solution that allowed for commonality in ammunition among the two types of tanks. Secondly was the fact that the M68A1E2 could employ the newly developed M900A1 APFSDS
depleted uranium round that had improved penetration performance in comparison to the M833. These early versions of the M1 Abrams were in active Army service until 1991 and with National Guard units until 1996. M1s built after 1984 were armed with the 120mm M256 and designated the M1A1. Many earlier M1 and IPM1 tanks were refitted with the M256 and their designations changed to the M1A1.
The
M1128 Stryker Mobile Gun System (MGS) carries the M68A1E4 105mm cannon. The principal function of the MGS is to provide rapid direct fire to support assaulting infantry. The cannon is mounted in a low-profile, fully stabilized turret integrated into the Stryker chassis. The M68A1E4 is based on the M68A1E2 105mm cannon's design. It has a sustained fire rate of six rounds per minute. The gun employs four types of cartridges. The M900A1 kinetic energy penetrator to destroy armored vehicles; the M456A2 high explosive anti-tank round to destroy thin-skinned vehicles and provide anti-personnel fragmentation; the M393A3 high explosive plastic round to destroy bunkers, machine gun and sniper positions, and breach openings in walls for infantry to access; and M1040 canister shot for use against dismounted infantry in the open. The M68A1E4 will be completely withdrawn from US service when the M1128 Mobile Gun System is retired by the end of 2022.
Other users
The gun was subsequently adopted for use on the German
Leopard 1 (for which the L7A3 variant was developed). In addition, several countries have used the gun to improve the
firepower of existing main battle tanks. Derivatives have even been mounted in Warsaw Pact-built
T-54 and T-55
The T-54 and T-55 tanks are a series of Soviet main battle tanks introduced in the years following the Second World War. The first T-54 prototype was completed at Nizhny Tagil by the end of 1945.Steven Zaloga, T-54 and T-55 Main Battle Tank ...
tanks in Israel, India, Egypt and Iraq, and
Type 79 tanks in China.
Variants
UK models
* L7A1
:Standard UK production variant.
* L7A2
:L7A1 fitted with a thermal sleeve.
* L7A3
:Variant for the (West) German
Leopard 1 MBT. The upper rear corner of the breech block reduced in size so gun can be depressed without hitting the turret roof.
* L7 LRF
:Low Recoil Force (LRF) version of the L7 used by the
Stingray light tank.
* Royal Ordnance 105mm IWS
:A development by Royal Ordnance designated Improved Weapon System with an increased chamber pressure and a longer barrel length of L/63.4.
* FM K.4 Modelo 1L
:
Argentine Army's licence produced by
Fabricaciones Militares in Argentina. Used on the
TAM medium tank. Also designated as "105 mm FRT L51 Tank Gun".
Chinese models
*Type 79/81/81A/83
:Chinese produced L7. Licence procured from Austria.
* ZPL-79
:Chinese licence-built designation for the L7A3 with replaceable indigenous thermal sleeve. Also known as Type 79. It was mounted on the
Type 80 tank prototypes.
* ZPL-81/A
:Modified Type 79. ZPL-81A has improved thermal sleeve. First seen on the
Type 59-II tank.
* ZPL-83/A
:Modified Type 81 with longer barrel and improved construct material. Also known as Type 83. It was fitted on the
Type 59D1,
Type 63HG,
Type 79 tank and
Type 88B tank.
* ZPL-94
:Modified Type 83 with longer barrel at 62 caliber. Mounted on
Type 59D tank and
Type 88A tank.
* ZPL-98
:Modified Type 83A rifled gun with an indigenous low recoil
muzzle brake and lighter weight. It was mounted on the
Type 63A amphibious tank. Also known as Type 98 rifled gun.
*ZPL-98A
:Modified Type 98 rifled gun, mounted on
ZTD-05 and
ZTL-11.
Other developments
*GT-3
:South African variant built by
Denel for converting Centurion with
20-pounder gun into
Olifant tanks. GT-3 retained the breach assemblies of 20-pounder paired with the modified copy of L7 barrel.
*GT-7
:South African variant built by Denel for the
Olifant Mk1A and
Rooikat 105. Incorporates a heavily modified recoil assembly.
*Rheinmetall Rh-105 family
:Multiple variants of 105 mm tank gun developed from L7 by
Rheinmetall
Rheinmetall AG is a German automotive and arms manufacturer, headquartered in Düsseldorf, Germany. Its shares are traded on the Frankfurt stock exchange.
History
Rheinmetall was founded in 1889. Banker and investor Lorenz Zuckermandel
L ...
of Germany for commercial market. The family consisted of Rh 105-60, Rh 105-40, Rh 105-30, Rh 105-20, and Rh 105-11. The last two numbers on the designation denotes the gun recoil force in metric ton. The Rh 105-20 and -11 models were fitted with muzzle brake and intended to be mounted on light tanks and wheeled armored vehicles. The variants has been fitted as modification on various armored vehicles, such as Rh 105-30 on Spanish M47E2, Rh 105-20 on
Ikv 91
The Infanterikanonvagn 91 ("infantry cannon wagon 91"), Ikv 91, was a high mobility assault gun that was developed to meet the operational requirements of the Swedish Army. It was designed and manufactured by Hägglund and Söner (now Hägglunds ...
and
AMX-10 RC, and Rh 105-11 on
MOWAG Shark.
*L74
:Swedish model built by
Bofors for the
Strv 103 using more sophisticated recoil assembly and a longer L/62 gun tube for increased muzzle-velocity and accuracy.
Usage
L7 variant
*
Centurion: L7A1 cannon on late Centurion models and derivatives such as
Olifant
*
Vickers MBT: Mark 1,
Mark 3
Mark 3 is the third chapter of the Gospel of Mark in the New Testament of the Christian Bible. It relates a conflict over healing on the Sabbath, the commissioning of the Twelve Apostles, a conflict with scribes and a meeting of Jesus with h ...
, and
Mark 4 models
**
Vijayanta
*
Leopard 1: L7A3 cannon
*
Leopard 2AV: Some of the prototype fitted with L7A3
*
M48 Patton: in some upgraded variants
**M48A2GA2: West German modification
**Super M48: German modernization of M48A2 or M48A3
**M48A5E: Spanish modification
**M48A5T2: Turkish modification
*
Stingray light tank: LRF cannon
*
M41 Walker Bulldog: LRF cannon on M41 105 variant
*
LAV-600
The Cadillac Gage LAV-600, also known as the V-600,Army Weaponry and Equipment, Page 469. Army: The Magazine of Landpower. Volume 36, Issue No 10. October 1986. is an American light armored 6×6 wheeled vehicle, derived from the LAV-300. Developed ...
: LRF cannon
*
T-54/55: in some upgraded variants
**
Type 59-II: Chinese modification of T-54
**
Type 59 Royal Ordnance: British modernization of Type 59
**
Tiran-4Sh: Israeli modification of T-54, both L7 and M68 variants fitted
**
Tiran-5Sh: Israeli modification of T-55, both L7 and M68 variants fitted
**
T-55M3: Israeli modernization of T-54/55
**
T-55 "Gulmohar": Indian modernization of T-55
**
M-55S
The T-54/T-55 tank series is the most widely used tank in the world and has seen service in over 50 countries. It has also served as the platform for a wide variety of specialty armored vehicles.Miller, David ''The great Book of Tanks'' Salama ...
: Slovenian modernization of T-55
*
Charioteer: A single prototype up-gunned with L7 cannon
*
FV4401 Contentious
FV 4401 ''Contentious'' was a prototype British air-portable tank destroyer of the early 1960s. At least one prototype was constructed and tested, although no production vehicles were built or saw service.
Project ''Prodigal''
The vehicle w ...
: The only prototype was later up-gunned with L7 cannon
*
Panzer 58: Production model
*
Panzer 61
*
Panzer 68
*
TAM medium tank
*
Rooikat 105
*
TH-400 and TH-800
ZPL variant
*
T-54/55: ZPL-83 in some upgraded kits sold by China
*
Type 59: in some upgraded variants
**Type 59-II: ZPL-79, ZPL-81
**Type 59-IIA: ZPL-81A
**Type 59D1: ZPL-83A
**Type 59D: ZPL-94
*
Type 69
The Type 69 () and Type 79 () are Chinese second generation main battle tanks. Both were developments of the Type 59 medium tank (a locally produced Soviet T-54A) with technologies derived from T-62. They were the first indigenously developed ...
: in some upgraded variants
**
Type 69-IIG: An upgraded Bangladeshi variant of
Type 69 tank
**
Type 79: ZPL-83
**
Type 79-II: ZPL-83A
*
Type 80: ZPL-79
**Type 85-I: ZPL-79
**Type 85-II: ZPL-94
**Type 88: ZPL-83A
**Type 88A: ZPL-94
*
Type 62G: ZPL-98 modification
*
Type 63: in some upgraded variants
**Type 63HG: ZPL-83A modification
**
Type 63A: ZPL-98
*
WMA301: Modified ZPL-94
*
ST-1: Modified ZPL-94
*
ST-2
''ST-2'' is a telecommunications satellite made by Mitsubishi Electric. It was launched on May 20, 2011 atop an Ariane 5 ECA rocket from ESA's Guiana Space Centre in a dual-launch mission with GSAT-8.
a
ST-2 is a replacement for the ST-1 satel ...
: Modified ZPL-94
*
ZTD-05: ZPL-98A
*
ZTL-11: ZPL-98A
*
ZTQ-15
The Type 15 (, also designated ZTQ-15), nicknamed the Black Panther (), is a Chinese third generation light tank operated by the People's Liberation Army Ground Force and People's Liberation Army Navy Marine Corps. It could become a successor to t ...
: Modified ZPL-94
Related designs with compatible ammunition
*
MB-3 Tamoyo III
*
EE-T1 Osório
*
OF-40
The OF-40 is an Italian main battle tank developed as a joint venture between OTO Melara and Fiat, and intended primarily for export sales. OTO Melara would develop and produce the hulls, and automotive components would be provided by Fiat (the ...
*
Strv 103
*
VT 1-1
*
M47 Patton: in some upgraded variants
**M47E2: Spanish modification armed with a Rheinmetall RH-105/30 gun
**M47 OTO: Italian modification armed with an
OTO Melara
OTO Melara was a subsidiary of the Italian company Finmeccanica, today Leonardo, active in the defence sector, with factories in Brescia and La Spezia. The Mod 56 pack howitzer, in service throughout the world, and the 76mm naval gun, ado ...
105mm/52 gun
*
Marder Medium Tank: Marder IFV armed with OTO Melara 105mm/52 gun
*
B1 Centauro: Italian wheeled armored vehicle with OTO Melara 105mm/52 gun
*
Type 16 Maneuver Combat Vehicle: Japanese wheeled armored vehicle with
Japan Steel Works 105mm/52 gun
Specification (L7A1)
*Calibre: 105 mm (4.13 in)
*Cartridge:
105×617mmR
The 105×617mm (4.1 inch) also known as 105×617mmR is a common, NATO-standard, tank gun cartridge used in 105mm guns such as those derived from the Royal Ordnance L7.
The 105×617mmR cartridge was originally developed from the calibre Ordnanc ...
*Barrel length: 52 calibres,
*Weight:
*Length:
*Rate of fire: 10 rounds per
minute
The minute is a unit of time usually equal to (the first sexagesimal fraction) of an hour, or 60 seconds. In the UTC time standard, a minute on rare occasions has 61 seconds, a consequence of leap seconds (there is a provision to insert a nega ...
(maximum)
*Range:
Notes
References
Bibliography
*
*
*
Starry, Donn A., General. "Mounted Combat In Vietnam." Vietnam Studies.
Department of the Army
The United States Department of the Army (DA) is one of the three military departments within the Department of Defense of the U.S. The Department of the Army is the federal government agency within which the United States Army (U.S.) is or ...
. First printing 1978.
* Zaloga, Steven J. and Hugh Johnson (2004). ''T-54 and T-55 Main Battle Tanks 1944–2004''. Oxford: Osprey.
{{ModernUSInfWeaponsNav
Cold War artillery of the United Kingdom
Tank guns of the United Kingdom
105 mm artillery
Military equipment introduced in the 1950s