M115 - 8in Howitzer


The Westervelt Board recommended the development of a howitzer with a calibre of approximately 8 in (203 mm) mounted on a carriage with an elevation of 0 to +65, a traverse of 360 and a maximum range of 18,000 yards (16,460 m). It was also stated that it would be desirable for a carriage to be developed which could mount either an 8 in howitzer or a 155 mm gun. There were two 8 in howitzers subsequently developed, the M1920 and the M1920M1, plus a carriage which could also be used for a 155 mm gun. Owing to a shortage of funds the project was suspended until 1927. Between 1927 and 1929 the carriage was redesigned for high-speed transport and the breech ring of the 8 in howitzer modified. The howitzer was known as the T2 and was to have a centrifugally cast barrel but as facilities for centrifugal casting were not then available, it was decided to design a barrel of cold-worked forged steel under the designation T3. Tests of the T3 howitzer began at Aberdeen Proving Ground in 1939 and the following year the T3 howitzer was standardised as the 8 in Howitzer M1 and the 155 mm Gun/8 in Howitzer Carriage T2E1 with minor modifications was standardised as the M1. After the Second World War the complete weapon was redesignated the Howitzer, Heavy, Towed: 8 in: M115. This consisted of Cannon Howitzer M2 or M2A1, Recoil Mechanisms M4 series (M4, M4A1, M4A2 or M4A3), and Carriage M1.


The cannon consists of the barrel, breech ring and breech mechanism. The M2A1 cannon is ballistically and physically interchangeable with the cannon M2, the major difference being that the M2A1 has been constructed with stronger steels. The carriage consists of equilibrator assemblies, elevating and traversing mechanisms, two single-wheel, single-axle heavy limber M5, two-axle bogie with eight tyres and two trails. Four spades, carried on the trails, are used to emplace the weapon. In recent years some armies have towed the weapon without the limber. The M115 fires the following separate loading ammunition: HE (M106) with the projectile weighing 92.53 kg, maximum muzzle velocity of 587 m/s to a maximum range (charge 7) of 16,800 m HE (M404) (carries 104 M43A1 grenades) with the projectile weighing 90.72 kg, maximum muzzle velocity of 587 m/s to a maximum range (charge 7) of 16,800 m HE (M509) (carries 195 M42 grenades) with the projectile weighing 93.66 kg, maximum muzzle velocity of 594.4 m/s to a maximum range of 16,000 m The carriage of the 8 in howitzer is also used to mount the 155 mm Gun M1 (Long Tom), which is still in use with some armies. In many countries the 8 in M115 has been replaced by a self-propelled version called the M110, details of which are given in the Self-propelled guns and howitzers (tracked) section. Versions of the M110 with the longer barrel are the M110A1 (no muzzle brake) and the M110A2 (fitted with muzzle brake). In most countries the M115 and the M110 have been phased out of service due to short range. In NATO service their prime mission was to fire nuclear rounds which have now been phased out of service.


Calibre: 203.2 mm
Barrel length: 5.142 m
Muzzle brake: none
Recoil system: hydropneumatic Breech mechanism: interrupted screw stepped thread
Carriage: split trail with limber
Shield: no
(travelling order) 14,515 kg
(firing position) 13,471 kg
(travelling) 10.972 m
(travelling) 2.844 m
(firing) 6.857 m
(travelling) 2.743 m
Ground clearance: 0.318 m
Track: 1.98 m
Tyres: 11.00 x 20
Elevation/depression: +65/-2
(total) 60
Rate of fire:
(max) 1 rd/min
(sustained) 1 rd/2 min
Max range: 16,800 m
Crew: 14
Towing vehicle: M125 (6 x 6) truck

Status : Pakistan has 26 of these.