m777 the lightweight route to 155 mm firepower

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A projectile leaves the barrel of an M777howitzer (Photo by BAE Systems)

Defence Procurement International - Summer 2016

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ORDNANCE & MUNITIONS

M777 – The Lightweight Route To155 mm FirepowerThe M777 howitzer has transformed modern-day artillery with its rapid

deployability, light weight and ability to fire the latest long-range, precision-guided

munitions.

By Doug Richardson





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Benet Labs and the Picatinny Arsenal have modified an M777A2 to install a 52-calibre barrel in place of the standard 39-calibre barrel, as part ofa project to develop long-ranged artillery. (Photo by US Army)

including Raytheon Missile Systems’ and

BAE Systems’ M982 Excalibur and the

Bofors 155 Bonus. Standard unassisted

projectiles can achieve a range of 15

miles (24 km), while assisted projectiles

can reach 19 miles (30 km). Excalibur

precision-guided munitions have a

maximum range of more than 25 miles

(40 km) with a Circular Error Probable

accuracy of less than 10 m.

RAPID EMPLACEMENT

Future projectiles are expected to in-

clude the Multi-Service Standard Guided

Projectile (MS-SGP), a sub-calibre

127 mm rocket-assisted projectile fitted

with sabots. Being developed by BAESystems, this will draw on technology

from the US Navy’s 155 mm Long

Range Land Attack Projectile (LRLAP) and

could have a maximum range of

100 km.

Although normally crewed by a team

of seven, the M777 can be operated by

five. Rapid insertion and extraction are

key factors in battlefield survivability.

The old M198 howitzer took more than

six-and-a-half minutes to emplace at

a new firing position, and more than10 minutes to displace, but the cor-

responding times for the M777A2 are

less than two-and-a-half minutes. The

sustained rate of fire is two rounds per

minute, rising to four rounds per minute

in rapid fire.

The M777 has seen combat service

in Iraq and Afghanistan, starting in

2006. Although it is a relatively modern

weapon, the US DoD is already taking

In February 2016, the United States

formally approved India’s planned

procurement of 145 BAE Systems

M777 155 mm howitzers for the Indian

Army under a Foreign Military Sales

(FMS) deal worth an estimated $700

million. The deal will make India the

fourth nation to adopt the weapon.

India’s planned procurement was

bogged down with delays to the point

where BAE Systems began to close down

its production facilities for the weapon,

having completed all existing orders.

But in June last year, the Indian

Ministry of Defence (MoD) reissued

its earlier letter of request to the US

government for the planned deal. In

order to meet an earlier commitmentto establish an in-country assembly,

integration and test facility for the

M777, in February this year, BAE

revealed that it had selected the Indian

company Mahindra as its business

partner for the proposed Indian

programme.

Although the 155 mm howitzer has

become the weapon of choice for many

armies, its range and firepower comes at

a price. This is a relatively heavy weapon

that in towed form can weigh typically7,000 – 9,000 kg and requires a crew

of eight or more. In the early 1980s, the

UK company Vickers Shipbuilding and

Engineering (now part of BAE Systems),

conceived the idea of using modern

materials and fabrication methods to

create a weapon that was approximately

3,000 kg lighter than the widely-used

M198 255 mm howitzer. The goal was to

achieve a total weight of not more than

4,000 kg. When briefed on the concept,

the US Army agreed that if the company

developed such a weapon, the service

would submit this to a full evaluation.

Efficient structural design was required

to minimise the weapon’s weight. One

weight-saving measure was the use of

high-strength titanium alloy in many of the

major structural parts. Another was the

use of hydraulics to operate the breech,

load tray, recoil and wheel arms. Together,

these measures led to weight savings of

more than 3,000 kg. In June 1989, firing

trials of what was then designated the

155 mm Lightweight Howitzer

commenced. Trials in the US started

soon afterwards and the weapon wassubsequently adopted by the US Army

and Marine Corps (USMC). Low-rate

initial production of what was formally

designated the M777 began under

a 2002 contract worth $135 million.

This resulted in the first howitzers being

delivered in 2003 to the USMC, the first

to take the weapon into service. A joint-

service multi-year contract for full-rate

production was awarded in 2005.

The basic M777 variant uses optical

fire control. The addition of an on-boardpower source, satellite navigation and

inertial navigation subsystems, a radio,

Gun Display Unit and Section Chief

Assembly, created the digitised M777A1.

The M777A2 standard adds a Block

1A software upgrade and an Enhanced

Portable Inductive Artillery Fuze-Setter for

use with Excalibur precision munitions.

The weapon is compatible with the

full range of 155 mm projectile types,




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steps to ensure its long-term support. In

September 2010, Anniston Army Depot

began a pilot programme to develop the

skills and facilities needed to overhaul

the M777.

Until recently, any damage to the

cradle of a M777 took the weapon out

of service, but BAE Systems engineers in

Hattiesburg, Mississippi, have devised a

way of using a laser tracker to accurately

measure the movement of the howitzer’sbarrel through its full arc of motion. This

data allows specifications to be devised

for replacement slipper pads (the metal

spacers, which slide along a runner

as the weapon is raised and lowered),

components that must be custom-made

to provide the exact fit needed to main-

tain the gun’s accuracy. Installation of

the new pads allows the weapon to be

returned to service.

In May this year, BAE Systems an-

nounced a teaming agreement withEmirates Defence Technology, which

includes a proposal to develop a self-

propelled system that would integrate

the M777 with EDT’s Enigma 8x8

Armoured Modular Fighting Vehicle.

The US Army’s Extended Range Cannon

Artillery (ERCA) project funded by the

US Army Armament Research, Develop-

Canadian M777 howitzers in action during a deployment to Afghanistan (Photo by Canadian Armed Forces)

ment and Engineering Center’s science

and technology office is intended to

develop the technologies needed to

extend the range of all 155mm artillery.

It is developing the new XM907 can-

Dressed in motion-capture suits, an M777 gun crew operate the weapon so that their bodymovements can be recorded to create computer-generated characters that will play the rest ofthe gun crew in a computerised training system for the M777A2. (US Army photo)





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non, XM1113 rocket-assisted projectile,

XM654 supercharge, an autoloader,

and new fire-control system. The Pro-

gram Manager Towed Artillery Systems

(PM-TAS) dual-funded Army and USMC

programme hopes to adapt the ERCA

cannon to the M777 to determine the

viability of a cross-platform solution that

would include a towed M777ER.

Engineers from Benet Labs and the

Picatinny Arsenal have modified an

M777A2 to install an existing 52-

calibre barrel modified to match the

weight of the proposed XM907 cannon,

in place of the current 39-calibre bar-

rel. The new configuration adds about

1.8 m to the system’s barrel length andaround 450 kg to the overall weight.

External grooves on the barrel allow

engineers to install weights at different

positions in order to move the weapon’s

centre of gravity forward or rearward

as required.

There are no plans to conduct firing

trials, but the modified M777 will be

towed in different weight and centre-of-

gravity configurations in order to dem-

onstrate that the re-barrelled weapon

still meets mobility requirements. Tests

will also be conducted to determine

how difficult it might be to elevate and

traverse. Component fabrication for

the M777ER is due to begin in the first

quarter of 2018, with hardware inte-

gration expected to end by mid-2020.

GUN OR HOWITZER?

Invented in Sweden towards the end of

the 17th century, the original howitzers

were designed to fire a cast-iron projec-

tile filled with gunpowder or incendiary

material, rather than the solid round

shot fired by the cannons of the time.

They used a smaller propelling charge

than guns, so needed a greater eleva-tion angle to achieve a given range.

This gave the projectile a steep angle

of descent that allowed it to land in the

interior of fortifications.

By the early 20th century, artillery

weapons that fired projectiles at higher

velocities, but at maximum elevation

angles of less than 35 degrees, were

classified as guns, while shorter-ranged

weapons with shorter barrels that fired

projectiles at lower velocities and an

maximum elevation angles of 45 degrees

or more were classified as howitzers.

This distinction became blurred during

the First World War, as the maximum el-

evation angle of guns began to increase,

as did the barrel length of howitzers. The

resulting weapons became known as

gun-howitzers, or simply howitzers.

Since the Second World War, most

land-based artillery pieces have com-

bined high muzzle velocity, long barrels,

long range, and maximum elevation

angles greater than 45 degrees. As a

result, the terms gun, howitzer, and gun-

howitzer are used interchangeably.

ABOUT THE AUTHOR

Following an earlier career in en-

gineering, Doug Richardson is a

defence journalist specialising in topics

such as aircraft, missiles and military

electronics. The author of more than

20 books on various defence topics,

between 1998 and 2013 he was the

editor of the monthly title Jane’s Missiles

& Rockets. He also writes for the Journal

of Electronic Defense.

Soldiers with Battery C, 1st Battalion, 321st Airborne Field Artillery Regiment, 18th Fires Brigade, 82nd Airborne Division, fire a 155 mm roundfrom an M777 at Forward Operating Base Bostick, in Onar Province, Afghanistan. (US Army photo)

m777 the lightweight route to 155 mm firepower

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