8-inch Mk. VI railway gun

The 8-inch Navy gun Mk.VI M3A2 on railway mount M1A1 was a World War II improved replacement for the World War I-era 8-inch (203 mm) M1888 gun and was used by the US Army's Coast Artillery Corps in US harbor defenses. The guns were also mounted in fixed emplacements on the barbette carriage M1A1.[1] These guns were US Navy surplus 8"/45 caliber guns from battleships scrapped under the 1922 Washington Naval Treaty. Mark VI (also Mark 6) was the Navy designation. The Army designation for this gun was "8-inch Navy gun Mk.VI M3A2".[1]

8-inch Mk.VI M3A2 railway gun
8-inch Mk.VI M3A2 railway gun
TypeRailway gun
Place of originUnited States
Service history
In service1941–1946
Used byUnited States
WarsWorld War II
Production history
ManufacturerBaldwin Locomotive Works (railway carriage)
Produced1941
No. built32? railway version, 16 fixed barbette mounts[1]
Specifications
Masstube and breech: 42,000 lb (19,000 kg)
complete railway mount: 188,000 lb (85,000 kg)[1]
Lengthtube and breech: 30 ft 9 in (9.37 m)

Shellseparate loading HE and AP,
260 pounds (120 kg) AP[2]
Caliber8 inches (203 mm)
BreechInterrupted screw, step cut (Welin type)
RecoilHydro-pneumatic
CarriageM1A1 railway
Elevation45 degrees
Traverse360 degrees
Rate of fire2 rounds a minute
Muzzle velocity2,750 ft/s (840 m/s) AP, or 2,840 ft/s (870 m/s) HE.
Maximum firing range35,300 yd (32,300 m)[2]
Feed systemhand
8-inch Navy MkVIM3 gun on barbette mount M1A1, as used by the Army in coast defense.

History

The ex-Navy Mark VI railway gun was quickly put together at the start of World War II, to supplement the older World War I 8-inch M1888 railway gun. It was developed from an experimental 12-inch (305 mm) railway howitzer carriage of World War I.[3] The all-around rotating mount and outriggers were designed to allow the gun to track a moving target for coast defense. These guns had a very short life in Army use, entering service in February 1941 and being cut up for scrap immediately after the war. The guns were the Navy's 8-inch (203 mm)/45 caliber Mark VI, and were originally secondary armament on Virginia- and Connecticut-class battleships launched 1904-06 and scrapped in the 1920s.[4] They were mounted in both fixed emplacements and on the M1A1 railway carriage.[1]

Deployment

Sighting and fire control equipment

The following sighting equipment was used with the gun.

  • M1 Deflection board
  • M1 fire adjustment board
  • M1A1 Range correction board
  • M3 Spotting board
  • M1912 Clinometer
  • M1 Percentage corrector
  • M1A1 Height finder, or M2A1
  • M6 Azmuth indicator
  • M5 Elevation indicator
  • M1910A1 Azmuth instrument
  • M8 Helium filling kit
  • M1 Gunners quadrant
  • Type B, set forward rule
  • M1 prediction scale
  • bore site
  • firing table, 8-I-1.[7]
  • M7 stereoscopic trainer
  • M1 generating unit

Support cars

  • M2 fire control car
  • M1 machine shop car
  • modified box car for ammunition

Surviving Examples

Four weapons of this type survive:[8]

  • One gun at Fort Miles, Delaware, on M1 railway proof mount (experimentally bored out to 9.12 in (232 mm)) (was previously at Naval Surface Warfare Center Dahlgren Division, Dahlgren, VA[9]
  • Two 8-inch Guns Mk VI M3A2 (#160L2 & #154L2), Battery 404, Fort Abercrombie, Kodiak, AK
  • One 8-inch Gun Mk VI M3A2 (#134L2), Kodiak Airport, Kodiak, AK (gun formerly at Battery 403, Fort J.H. Smith, Kodiak, AK)

See also

References

  1. Berhow 2004, pp. 114-117.
  2. Berhow 2004, p. 61.
  3. Lewis 1979, p. 109.
  4. "USA 8"/45 (20.3 cm) Mark 6". NavWeaps.com.
  5. Berhow 2004, p. 226.
  6. Lewis 1979, pp. 140-141.
  7. "FT 8-I-1 Firing tables". Gene Slovers US Navy Pages.
  8. Berhow 2004, p. 234
  9. "Railway Batteries". FortMiles.org. Archived from the original on 2018-09-28. Retrieved 2012-11-07.
  • TM 9-2300 Standard Artillery and Fire Control Material. 1944.
  • "TM 9-463" (PDF).
  • SNL E-34
  • "FM 4-49" (PDF). Archived from the original (PDF) on 2010-12-19. Retrieved 2010-08-27.
  • Berhow, Mark A., ed. (2004). American Seacoast Defenses, A Reference Guide (second ed.). CDSG Press. ISBN 0-9748167-0-1.CS1 maint: ref=harv (link)
  • Lewis, Emanuel Raymond (1979). Seacoast Fortifications of the United States. Annapolis, Maryland: Leeward Publications. ISBN 978-0-929521-11-4.CS1 maint: ref=harv (link)
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