View source for BL 4 inch naval gun Mk VII

{{Infobox Weapon
|name= Ordnance BL 4 inch gun Mk VII
|image=[[Image:BL4inchMkVIIGunHMASAustralia1918.jpg|300px]]
|caption=On [[:en:HMAS Australia (1911)|HMAS ''Australia'']], 1918
|origin={{flagicon|United Kingdom}} [[United Kingdom of Great Britain and Ireland|United Kingdom]]
|type= [[Naval gun]]
<!-- Type selection -->
|is_ranged=yes
|is_explosive=
|is_artillery=yes
|is_UK=yes
<!-- Service history -->
|service=1908 - 1945
|used_by={{flagicon|United Kingdom}} [[United Kingdom of Great Britain and Ireland|United Kingdom]]
|wars= 
<!-- Production history -->
|designer= 
|design_date=
|manufacturer=
|production_date=
|number=600
|variants= 
<!-- General specifications -->
|weight={{convert|4704|lb|kg|sigfig=3}} (barrel & breech)<ref name=Handbook1913/>
|length=
|part_length={{convert|201.25|in|m|sigfig=4}} bore (50.3 [[Caliber#Caliber_as_measurement_of_length|calibres]])<ref name=Handbook1913>HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913</ref> 
|width=
|height=
|crew=
<!-- Ranged weapon specifications --> 
|cartridge={{convert|31|lb|kg|sigfig=4}} [[British ordnance terms#Common Pointed|Common pointed]], [[British ordnance terms#Common Lyddite|Common lyddite]]<ref name=Handbook1913/>
|caliber={{convert|4|in|mm|sigfig=4}}
|action= 
|rate=
|velocity={{convert|2852|ft/s|m/s}}<ref>2852 ft/second firing a 31 lb 3 [[British ordnance terms#C.R.H.|C.R.H.]] projectile, using 9 lb 5 oz 15 drams cordite MD size 16 propellant. HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913.</ref>
|range= 
|max_range={{convert|11600|yd|m}} at 15°<ref name=Warship53>Campbell, ''Warship Volume X'', p. 53.</ref>
|sights= 
<!-- Artillery specifications -->
|breech=[[Welin breech block|Welin]], Single-motion screw<ref name=Handbook1913/>
|recoil=
|carriage=
|elevation=
|traverse=
}}
The '''[[British ordnance terms#BL|BL]] 4-inch gun Mk VII''' was a British high-velocity naval gun introduced in 1908 as an anti-[[torpedo boat]] gun in large ships, and in the main armament of smaller ships<ref name=Handbook1913/>.  It was also used as a defensive weapon on [[Defensively Equipped Merchant Ships]] (DEMS) during the [[Second World War]].<ref name=Warship53/>

==Naval history==
The guns armed the following warships :
*[[Bellerophon class battleship|''Bellerophon'' class battleships]] laid down 1906
*[[St. Vincent class battleship|''St. Vincent'' class battleships]] laid down 1907
*[[Boadicea class cruiser|''Boadicea'' class scout cruisers]] laid down 1907
*[[HMS Neptune (1909)|HMS ''Neptune'']] laid down 1909
*[[Colossus class battleship (1910)|''Colossus'' class battleships]] laid down 1909
*[[Indefatigable class battlecruiser|''Indefatigable'' class battlecruisers]] laid down 1909
*[[Orion class battleship|''Orion'' class battleships]] laid down 1909
*[[Lion class battlecruiser|''Lion'' class battlecruisers]] laid down 1909
*[[Town_class_cruiser_(1910)#Bristol_class|''Bristol'' class light cruisers]] laid down 1909
*[[Blonde class cruiser|''Blonde'' class scout cruisers]] laid down 1909
*[[Active class cruiser|''Active'' class scout cruisers]] laid down 1910
*[[King George V class battleship (1911)|''King George V'' class battleships]] laid down 1911

[[File:BL 4 inch Mk VII gun DEM 1943 LAC 3394508.jpg|thumb|left|<center>On a [[Defensively Equipped Merchant Ships|"DEMS" (defensively equipped merchant ship)]], 1943</center>]]
The gun was succeeded in the "heavy" 4-inch class on new warships commissioned from 1914 onwards by the  [[QF 4 inch Mk V naval gun|QF 4 inch Mk V]]. This new generation of warships were more heavily armed, and the BL Mk VII's role as secondary armament on [[capital ship]]s and primary armament on cruisers was taken over by the [[BL 6 inch Mk VII naval gun|BL 6 inch Mk VII]] and [[BL 6 inch Mk XII naval gun|BL 6 inch Mk XII]] while the 4-inch calibre became the secondary armament on cruisers and primary armament on destroyers.

In [[World War II]] many guns were used to arm merchant ships.
{{clearleft}}

==World War I field gun service==
[[Image:BL 4 inch Mk VII gun East Africa WWI.jpg|thumb|left|<center>East Africa, World War I</center>]]
A battery of 4 guns mounted on field carriages was first deployed with the South African Heavy Artillery in the [[South West Africa Campaign|German South West Africa campaign]] in 1915 and returned to England in September. They were then deployed in the [[East African Campaign (World War I)|East African Campaign]] from February 1916 with 11th Heavy Battery (renumbered 15th Battery from April 1916) manned by the Royal Marine Artillery.<ref>Farndale 1988, page 318</ref>
<br style="clear:left;" ><!--don't delete this, it forces next heading to nicely follow below the Images-->

==Image gallery==
<gallery>
Image:BL 4 inch Mk VII gun barrel diagram.jpg|<center>Barrel dimensions</center>
Image:BL 4 inch Mk VII Gun Breech Diagram.jpg|<center>Breech mechanism</center>
Image:BL 4 inch Mk VII Gun Percussion & Electric Locks Diagram.jpg|<center>Percussion and electric locks</center>
Image:BL 4 inch Mk VII gun on field carriage.jpg|<center>Field carriage as depicted in 1913 manual</center>
</gallery>

==Surviving examples==
[[Image:AucklandMuseum edit gobeirne.jpg|thumb|left|<center>Gun from [[HMS New Zealand (1911)|HMS New Zealand]] outside the [[Auckland War Memorial Museum]]</center>]]
*[http://www.geocities.com/kelburn.geo/4inchguns.html 2 Mk VII guns from HMS New Zealand] outside the [[Auckland War Memorial Museum]]
<br style="clear:left;" ><!--don't delete this, it forces next heading to nicely follow below the Images-->

==See also==
{{Commonscat-inline|BL 4 inch Mk VII naval gun}}
*[[4"/50 caliber gun]] US equivalent
*[[List of naval guns]]

==Notes==
{{Reflist}}

==References==
*[http://www.gwpda.org/naval/hb4_inch.htm HANDBOOK for the 4" Mark VII. and VIII. B.L. Guns 1913 (Corrected to September 1913.) ADMIRALTY Gunnery Branch, G.8652/13]
*{{cite journal |last=Campbell |first=John |editor=Lambert, Andrew D. |year=1987 |title=British Naval Guns, 1880&ndash;1945, No. 17 |journal=Warship Volume X |pages=pp.&nbsp;53&ndash;55 }}
*DiGiulian, Tony. [http://www.navweaps.com/Weapons/WNBR_4-50_mk7.htm British 4"/50 (10.2 cm) BL Mark VII]
*Farndale, General Sir Martin. [http://www.amazon.co.uk/dp/1870114051 History of the Royal Regiment of Artillery : Forgotten Fronts and the Home Base 1914-18. London:The Royal Artillery Institution, 1988]

==External links==


{{GreatWarBritishNavalWeapons}}
{{GreatWarBritishWeapons}}

[[Category:Naval guns of the United Kingdom]]
[[Category:100 mm artillery]]