8-inch Gun M1
| 8-inch Gun M1 | |
|---|---|
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| Type | Heavy gun |
| Place of origin | United States |
| Service history | |
| Used by | United States United Kingdom |
| Wars | World War II |
| Production history | |
| Designed | 1940–1944 |
| Produced | 1942-945 |
| Specifications | |
| Weight | Combat: 69,300 lb (31,400 kg) |
| Barrel length | 33 ft 4 in (10.16 m) L/50 |
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| Shell | separate-loading, bag charge |
| Caliber | 203 mm (8.0 in) |
| Breech | interrupted screw |
| Recoil | hydropneumatic |
| Carriage | split trail |
| Elevation | +10° to +50° |
| Traverse | 30° (initially), post-war 40° |
| Muzzle velocity | 2,840 ft/s (870 m/s) |
| Effective firing range | 12.5 mi (20.1 km) (minimum) |
| Maximum firing range | 20.24 mi (32.57 km) |
The 8 inch gun M1 was a 203 mm towed heavy gun developed in the United States. At 32,584 m (35,635 yds.), it had the longest range of any US Army field artillery weapon in World War II. It was also used in small numbers by the British Army.
Serious development began in June 1940 of an 8-inch (203 mm) gun that would have a range of 33,500 yards (30,600 m), a road speed of 25 mph (40 km/h), be transported in 2 loads weighing no more than 44,000 lb (20,000 kg) and be suitable for rail movement. The gun used the same projectile as the 8 inch coastal gun and the US Navy's 8 inch cruiser gun. Using the same carriage as the 240 mm howitzer M1 eased development, but the gun was very troublesome and wasn't standardized until January 1944. The main problems were excessive bore wear and poor accuracy, but it was felt that nothing better could be produced in a timely manner. Thus it entered production at a low rate and in small numbers. Only 139 weapon systems were produced before production ceased in 1945.
In the quest for greater tactical mobility, the Ordnance Department experimented with a self-propelled version. Like the 240 mm howitzer, it was mounted on a stretched Heavy Tank T26E3 chassis that had an extra bogie wheel per side as the 8in Gun Motor Carriage T93, but the war ended before they could be used and were later scrapped.
One of the requirements during development was that the gun be easy to emplace. Given the weight of the gun and carriage this was a challenge. Eventually, a pair of three-axle transport wagons were developed - one for the barrel/recoil mechanism and one for the carriage. These transport wagons were also used with the 240 mm howitzer. These were standardized as the M2 and M3. The six-wheeled wagon M2 carried the carriage and the M3 six wheeled transport carried the barrel and recoil system as shown below: This separate configuration required the use of the 20-ton M2 truck-mounted crane for set up. The crane included a clam-shell bucket that was transported on a trailer and used to dig the recoil pit for the gun. In spite of the weight and being transported in two pieces, the gun could be emplaced in two hours.
The transport wagons could be towed by heavy trucks; but, had problems in soft ground. The M6 High Speed Tractor which was designated for towing the 8 Inch Gun and 240mm Howitzer was not yet in product; so, the Ordinance Depart improvised. Obsolete M3 Lee medium tanks and depot storage M10 tank destroyer were quickly modified and tested. These proved to be satisfactory and were adopted for use as the M33 and M35 respectively.
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