View source for 6-inch/30-caliber gun

{{Infobox weapon
|name=6"/30 caliber Mark 1, 2, and 3
|image=USS Atlanta 6inch gun LOC cph 3b07972.jpg
|image_size=300
|caption={{USS|Atlanta|1884|2}}, 6-inch/30 caliber gun.
|origin= United States
|type=[[Naval gun]]
<!-- Type selection -->
|is_ranged=YES
|is_bladed=
|is_explosive=
|is_artillery=YES
|is_vehicle=
<!-- Service history -->
|service=1885
|used_by= [[United States Navy]]
|wars=
* [[Spanish–American War]]
* [[Philippine–American War]]
* [[World War I]]
<!-- Production history -->
|designer=[[Bureau of Ordnance]]
|design_date=1883
|manufacturer=[[Washington Navy Yard|U.S. Naval Gun Factory]]
|production_date=
|number=
* '''Mark 1''': 1
* '''Mark 2''': 20
* '''Mark 3''': 109
|variants=Mark 1, Mark 2 Mod 1 – Mod 3, Mark 3 Mod 0 – Mod 9
<!-- General specifications -->
|weight=
* '''Mark 1''': {{cvt|11010|lb}} (without breech)
* '''Mark 2''': {{cvt|10430|lb}}
|length=
* '''Mark 1''': {{cvt|189.7|in}}
* '''Mark 2''': {{cvt|193.53|in}}
* '''Mark 3 Mod 0 and Mod 3''': {{cvt|196|in}}
* '''Mark 3 Mod 1''': {{cvt|226|in}}
* '''Mark 3 Mod 2 and Mod 8''': {{cvt|256|in}}
|part_length=
* '''30 Caliber''': {{cvt|180|in}} bore (30 [[Caliber#Caliber as measurement of length|calibers]])
* '''35 Caliber''': {{cvt|210|in}} bore (35)
* '''40 Caliber''': {{cvt|240|in}} bore (40)
|width=
|height=
|crew=
<!-- Ranged weapon specifications -->
|cartridge=
* {{cvt|105|lb}} naval [[Armour-piercing shell|armor-piercing]]
|caliber={{cvt|6|in|0}}
|action=
|rate=
* As commissioned: 0.66 rounds per minute (bag guns)
* After 1906: 7.3 rounds per minute (bag guns)
* As commissioned: 1.5 rounds per minute (case guns)
* After 1906: 7.6 rounds per minute (case guns)
|velocity=
* {{cvt|1950|ft/s}} 30 caliber
* {{cvt|2000|ft/s}} 35 caliber
* {{cvt|2150|ft/s}} 40 caliber
|range=
* {{cvt|9000|yd}} at 15.3° elevation
* {{cvt|18000|yd}} at 30.2° elevation
|max_range=
|feed=
|sights=
<!-- Artillery specifications -->
|breech=
|recoil=
|carriage=
|elevation=
* '''Mark 3''': −7° to +12° (early units)
* '''Mark 3''': −10° to +12° (later units)
|traverse=−150° to +150°
}}

The '''6"/30 caliber gun Mark 1''' (spoken "six-inch-thirty-caliber") were used for the primary battery of the [[United States Navy]]'s [[dispatch vessel]] {{USS|Dolphin|PG-24|2}} with the '''Mark 2''' being used in the secondary batteries for its "New Navy" [[protected cruiser]]s {{USS|Atlanta|1884|2}}, {{USS|Chicago|1885|2}}, and {{USS|Boston|1884|2}} and the '''Mark 3''' used for the primary and secondary batteries in the succeeding early protected cruisers in addition to secondary batteries in the "Second Class Battleships" {{USS|Maine|ACR-1|2}} and {{USS|Texas|1892|2}}.{{sfn|Navweaps|2015}}{{sfn|Friedman|2011|pp=179–180}}

==Design==
The 6-inch/30 caliber Mark 1, 2, and 3 guns were developed before the [[Spanish–American War]] and still used [[black powder]] or [[brown powder]], in later years they were not considered strong enough to withstand the higher chamber pressures generated by the newer [[smokeless powder]] adopted around 1898 and were obsolete before the start of [[World War I]].{{sfn|Navweaps|2015}}

The Mark 1, gun No. 1, was constructed of [[Built-up gun|tube]], jacket, 16 [[Hoop gun|hoops]], an elevating band and integral [[trunnion]]s with a screwed on muzzle bell. The Mark 2 also trunnioned with the Mark 2 Mod 1 only having 10 hoops, jacket, and chamber liner and the Mod 2 the same but with a full-length liner. All Mark 1 and Mark 2 guns were constructed to a length of 30 calibers. In 1895 all Mark 2s were ordered to be converted to rapid-fire, fixed ammunition. This was done in 1898–1902 with gun No. 2 being delivered in November 1898 for use in ''Atlanta''.{{sfn|Navweaps|2015}}{{sfn|Friedman|2011|pp=179–180}}

The Mark 3 was trunnioned as the Mark 1 and Mark 2, but was built in three different caliber lengths, 30, 35, and 40, in eight different Mods, Mod 0 – Mod 6 and Mod's 8 and 9. Mod 0 was 30 caliber with Mod 1 being 35 caliber. All 30 and 35 caliber Mods had a liner, 10 hoops, and a jacket. Mod 2 was 40 caliber with only eight hoops. Mod 3 was again 30 caliber but introduced the use of case ([[Shell (projectile)#Separate loading cased charge|semi-fixed]]) ammunition. The Mod 4 was experimental in that it eliminated the trunnions and used a threaded sleeve. Mod 5s were reworked Mod 1s making them capable of handling case ammunition. As with the Mod 5 the Mod 6 were Mod 2s reworked to handle case ammunition. The Mod 7 was skipped and no drawings exist for this Mod. The Mod 8 was another Mod 2 rework, this time removing the trunnions and using a threaded sleeve. The last Mod was the Mod 9, using a Mod 3 gun and giving it a full-length liner.{{sfn|Navweaps|2015}}{{sfn|Friedman|2011|pp=179–180}}

==Naval Service==
{|class="wikitable"
!Ship
!Gun Installed
!Gun Mount
|-
|{{USS|Dolphin|PG-24}}
|Mark 1: 6"/30 caliber
|Mark 1: 1 × shifting pivot
|-
|{{USS|Atlanta|1884}}
|Mark 2: 6"/30 caliber
|Mark 2: 6 × muzzle pivot mount
|-
|{{USS|Boston|1884}}
|Mark 2: 6"/30 caliber
|Mark 2: 6 × muzzle pivot mount
|-
|{{USS|Chicago|1885}}
|Mark 2: 6"/30 caliber
|Mark 2: 8 × muzzle pivot mount
|-
|{{USS|Maine|ACR-1}}
|Mark 3: 6"/30 caliber
|Mark 3: 6 × central-pivot
|-
|{{USS|Texas|1892}}
|
* Mark 3: 4 × 6"/30 caliber
* Mark 3: 2 × 6"/35 caliber
|Mark 4: 6 × central-pivot w/single-piece slide
|-
|{{USS|Newark|C-1}}
|
* Mark 3: 6"/30 caliber (as built)
* Mark 3: 6"/40 caliber (refit 1901–1902)
|Mark 3: 12 × central-pivot
|-
|{{USS|Charleston|C-2}}
|Mark 3: 6"/30 caliber
|Mark 3: 6 × central-pivot
|-
|{{USS|Baltimore|C-3}}
|Mark 3: 6"/30 caliber
|Mark 3: 6 × central-pivot
|-
|{{USS|Philadelphia|C-4}}
|Mark 3: 6"/30 caliber
|Mark 3: 12 × central-pivot
|-
|{{USS|Columbia|C-12}}
|Mark 3: 6"/40 caliber
|Mark 3: 2 × central-pivot
|-
|{{USS|Minneapolis|C-13}}
|Mark 3: 6"/40 caliber
|Mark 3: 2 × central-pivot
|-
|{{USS|Yorktown|PG-1}}
|Mark 3: 6"/30 caliber
|Mark 4: 6 × central-pivot w/single-piece slide
|-
|{{USS|Petrel|PG-2}}
|Mark 3: 6"/30 caliber
|Mark 4: 6 × central-pivot w/single-piece slide
|-
|{{USS|Concord|PG-3}}
|Mark 3: 6"/30 caliber
|Mark 4: 6 × central-pivot w/single-piece slide
|-
|{{USS|Bennington|PG-4}}
|Mark 3: 6"/30 caliber
|Mark 4: 6 × central-pivot w/single-piece slide
|}

==Preserved weapons==
At least five guns of this type are preserved:
* One gun from ''Maine'' (ACR-1) in [[Washington, DC]] at the [[National Museum of the United States Navy]].{{sfn|Hartshorn|2015}}
* One gun from ''Maine'' (ACR-1) in [[Portland, Maine]] at [[Fort Allen Park]].
* One gun from ''Maine'' (ACR-1) at the city hall in [[Alpena, Michigan]].
* Two guns from ''Concord'' (PG-3) at the Veterans Memorial Museum, [[Chehalis, Washington]].

==See also==
===Weapons of comparable role, performance and era===
* [[BL 6 inch gun Mk II – VI]] approximate British equivalent

==Notes==
{{Reflist|2}}

==References==

* {{cite book
  | first=Norman
  | last=Friedman
  | author-link=Norman Friedman
  | url=https://books.google.com/books?id=yh3OAwAAQBAJ
  | title=Naval Weapons of World War One
  | publisher=Seaforth Publishing
  | year=2011
  | isbn=978-1-84832-100-7
  }}
* {{cite web
  |url=http://www.byronhartshorn.com/2015/02/24/visiting-the-uss-maine-around-washington-d-c/
  |last=Hartshorn
  |first=Byron
  |title=Visiting the USS ''Maine'' around Washington, DC
  |date=24 February 2015
  |access-date= 19 October 2016
  }}
* {{cite web
  |url=http://www.navweaps.com/Weapons/WNUS_6-30_mk1.htm
  |title=United States of America 6"/30, 6"/35 and 6"/40 (15.2 cm) Marks 1, 2, 3, 4 and 7
  |publisher=Navweaps
  |date=3 May 2015
  |access-date=15 May 2016
  |ref={{sfnRef|Navweaps|2015}}
  }}

==Further reading==
* {{cite book
  | last1 = Bauer
  | first1 = K. Jack
  | author-link = K. Jack Bauer
  | last2=Roberts
  | first2=Stephen S.
  | title = Register of Ships of the U.S. Navy, 1775–1990: Major Combatants
  | publisher = Greenwood Press
  | year = 1991
  | location = [[Westport, Connecticut]]
  | isbn = 0-313-26202-0
  }}
* {{cite book
  | last=Friedman
  | first=Norman
  |title=U.S. Cruisers: An Illustrated Design History
  |publisher=Naval Institute Press
  | year=1984
  | location=[[Annapolis, Maryland]]
  | isbn=0-87021-718-6
  }}

==External links==
{{Commons category}}
* [http://www.gwpda.org/naval/usn14gun.htm Bluejackets Manual, 1917, 4th revision: US Navy 14-inch Mark 1 gun]

{{WWIUSNavalWeapons}}

{{Use dmy dates|date=June 2017}}

{{DEFAULTSORT:6 30 Caliber Gun}}
[[Category:Naval guns of the United States]]
[[Category:152 mm artillery]]