The project for the 240 mm Howitzer M1 began in 1940 and after a couple of false starts, settled on a split trail design. It was provided with a 4 wheeled Carriage Transport Wagon on to which it could be lifted or winched when required to move. The barrel was also carried on a transport wagon. These early designs were later replaced by 6 wheeled versions. Towing was undertaken by the Tractor High-Speed M6 or various redundant tanks fitted with towing gear.
The design was approved and standardised in May 1943 although production had already started. Whenever possible, the gun was accompanied by a 20 ton Loraine Crane M2. This udsed its clamshell bucket to dig the pit needed for the recoil spades and to allow the gun to breech to recoil into at high elevations. The crane then lifted the carriage and gun into place. Using the crane, the gun could be brought into action in about 2 hours.
Without the crane, the pit had to be hand dug and the equipment emplaced using the winches on the M6 Tractors. The carriage was dragged from its wagon and across the pit. The trail legs were partly opened to form a ramp, up which the the gun transport wagon was winched and chained in place. The barrel could now be winched off the wagon and into the cradle. The gun wagon was then removed and the trail legs were fully opened. Emplacing the gun in this way could take anything from 8 hours upwards.
The 240 mm Howitzer M1 was an excellent weapon that saw extensive use, particularly in Italy. It served on after the war with both Britain and the USA into the late 1950’s. It was finally retired when stocks of ammunition built up during the war ran out.
Data
Howitzer M1 on Carriage M1
| Weight of Gun & Breech Mechanism | 25,261 lbs |
| Total Length | 331 inches |
| Rifling | 68 grooves, uniform right hand 1/25 |
| Breech Mechanism | Interrupted screw, drop block, percussion fired |
| Elevation | +15° to +65° |
| Traverse | 22½° |
| Recoil System | Hydropneumatic, constant, 56 inches |
| Weight in Action | 64,700 lbs |
Performance
Firing standard 360 lb HE Shell
| Muzzle Velocity | 2,300 feet/second |
| Maximum Range | 25,225 yards |
Ammunition
Seperate loading, bag charge
| Shell, HE, M114 | Streamlined shell fitted with Fuze PD M51 or MT M67. Later issues allowed fitting of the Proximity Fuze T76E6 |
| Propelling Charge | 4 unit charge consisting of a base unit & 3 increments |