5.5"/50 (14 cm) BL Mark I
Updated 29 February 2012

This weapon was introduced to British service when two cruisers being built for Greece, Antinavarhos Kontouriotis and Lambros Katsonis, were taken over at the start of World War I and then renamed HMS Birkenhead and HMS Chester, respectively.  Subsequently, this weapon was mounted on the battlecruisers Hood and Furious and later on the aircraft carrier Hermes.  This was the only gun obtained in such a manner ever to be adopted for use on other British ships.

This gun caliber was selected by the Greeks over the contemporary British 6" (15.2 cm) weapons because it fired a lighter shell than did the British 6" (15.2 cm) guns and as a result its ammunition could be more easily handled.  It is interesting to note that similar considerations led the Japanese to adopt the 14 cm (5.5") caliber for their light cruisers built after World War I.

During World War II, guns removed from the above ships were used to arm two AMC's while others were used for coastal defense batteries.  Two ex-HMS Hood guns were sent to Ascension Island, as shown in the photographs below.

These guns were built by Coventry Ordnance Works (COW) and were of wire-wound construction with a tapered inner A tube, A tube, full-length wire, B tube, overlapping jacket, breech ring and breech bush.  The Welin breech-block was manually operated with a Holmstrom mechanism.  A total of 81 guns were finished out of 246 originally ordered, of which 79 still existed in 1939.

As of 2006, at least five of these guns still exist:  One at the Imperial War Museum in London (formerly on HMS Chester), two on Ascension Island at Fort Benson (formerly on HMS Hood) and two on Stremoy Island (Faroe Islands) at Fort Skansin (formerly on HMS Furious).

Nomenclature note:  The 5.5"/42 (14 cm) BL Mark II was intended for DAMS of World War I, but this did not progress beyond the design stage, even though 1,100 guns were planned.  Construction would have been A tube, taper wire and full length jacket.  Weight without BM would have been 5.625 tons (5.72 mt).  Later 5.5" (14 cm) BL guns were Army howitzers of the World War II period.


Amidships layout of HMS Hood


Two former HMS Hood 5.5" (14 cm) guns reused as Coastal Artillery at Fort Bedford, Ascension Island
The gun shields are not the originals as used on HMS Hood
Photograph copyrighted by and use courtesy of Administrator's Office of Ascension Island


Breech of one of the above weapons
Engraving reads as follows:

B.L. 5.5-In wire Mark I. C.O.W. 1918
No 56

N = Navy and top of gun (orientation that results in the least amount of droop)
B.L. 5.5-In wire Mark I = Breech Loading 5.5 inch (14 cm) gun of wire wound construction Mark I
C.O.W. 1918 = Built at the Coventry Ordnance Works in 1918
No 56 = Serial number 56

Photograph copyrighted by and use here courtesy of Administrator's Office of Ascension Island

For an interesting story about these guns, see this Ascension Island Link (Wayback Archives)


5.5"/50 (14 cm) BL Mark I formerly on HMS Chester and now at the Imperial War Museum, London, UK
This gun is notable for having been manned by Boy First Class Jack Cornwell, who at age 16 was the second-youngest recipient of the Victoria Cross and who was mortally wounded at Jutland (Skagerrak)
Photograph copyrighted by Vladimir Yakubov


Identity and Maintenance Plates on above weapon
Photograph copyrighted by Shane Rogers

Images by Jan Egil Kristiansen

Gun #35 and Gun #42 at Fort Skansin

Regarding the description for Gun #42, "Holmstrom" is actually the type of breech mechanism

Gun Characteristics
Designation 5.5"/50 (14 cm) BL Mark I
Ship Class Used On
(see Note)
Birkenhead, Chester, Hood, Furious, Hermes and submarine K17

AMCs Laurentic and Montclare

Date Of Design About 1913
Date In Service 1915
Gun Weight 15,600 lbs (7,076 kg)
Gun Length oa 284.7 in (7.232 m)
Bore Length 275 in (6.985 m)
Rifling Length 235.9 in (5.992 m)
Grooves 40
Lands N/A
Twist Uniform RH 1 in 30
Chamber Volume 1,500 in3 (24.58 dm3)
Rate Of Fire 12 rounds per minute
Note:  It had been planned to use this gun on other K class submarines, but this was not carried out and instead they carried 4"/40 (10.2 cm) Mark XI guns.
Type Bag
Projectile Types and Weights
(see Note 2)
CPC - 82 lbs. (37.2 kg)
Common - 82 lbs. (37.2 kg)
Shrapnel - 82 lbs. (37.2 kg)
HE - 82 lbs. (37.2 kg)
Shellite - 82 lbs. (37.2 kg)
HENT - 82 lbs. (37.2 kg)
HE Mark ID - 82 lbs. (37.2 kg)
Bursting Charge 5.25 lbs. (2.4 kg)
Projectile Length N/A
Propellant Charge 1921:  22.25 lbs. (10.1 kg) MD19
1930:  22.54 lbs. (10.22 kg) SC115
Muzzle Velocity CPC - 2,790 fps (850 mps)
Others - N/A
Working Pressure 18 tons/in2 (2,531 kg/cm2)
Approximate Barrel Life N/A
Ammunition stowage per gun Hood:  See Note 2
Others: N/A

1) The propellant charge was in a single bag.

2) Outfit for Hood as built was 1,728 Lyddite, 582 common, 96 shrapnel, 464 practice.  After 1929-1931 refit, the outfit was 1,368 HE, 624 Shellite, 360 HENT, 50 starshell (forward shell room only) and 449 practice.

3) Shells were generally 4crh.  The HE Mark ID 8/16crh "streamlined" shell was developed during World War II.

4) Outfit included CPC and HE on all ships during World War II.

5) A reduced charge of 14.8 lbs. (6.7 kg) MD was used for practice rounds.

Elevation With 82 lbs. (37.2 kg) CPC Shell
Range @ 30 degrees 18,500 yards (16,920 m)
Range @ 25 degrees 16,000 yards (14,630 m)
Range @ 30 degrees 17,770 yards (16,250 m)
Note:  The first 30 degree value is from "Anatomy of the Ship:  The Battlecruiser Hood" and I believe that it is for Cordite MD.  The other values are from "Naval Weapons of World War Two" and I believe that they are for Cordite SC.
Mount / Turret Data
Designation Single Mounts

   Birkenhead and Chester (10):  PI
   Hermes (6), Furious (10), Laurentic (7) and Montclare (7):  PI*
   K17 (1):  PI**
   Hood (12):  CPII

Weight  PI and PI*:  N/A
CPII:  18.68 tons (18.89 mt) including shield
(see Note 3)
PI:  -7 / +15 degrees
PI*  -7 / +25 degrees
PI**:  -7 / +25 degrees
CPII:  -5 / +30 degrees
Elevation Rate Manually operated, only
Train about -150 / +150 degrees
Train Rate Manually operated, only
Gun recoil N/A

1) PI, PI*, PI** and CPII mounts were also used in coastal batteries.

2) Hood had two mounts removed 1938-1939 and the remainder in 1940.  Furious had all of her mounts removed during her 1931-1932 refit.

3) The PI** mounting used on K17 may actually have been limited to about +20 degrees as the gun barrel height was lower than on the PI* mounts.

Data from
"Naval Weapons of World War Two" by John Campbell
"Warships of World War II" by H.T. Lenton & J.J. Colledge
"Cruisers of the Royal and Commonwealth Navies" by Douglas Morris
"Anatomy of the Ship:  The Battlecruiser Hood" by John Roberts
Page History

20 February 2008 - Benchmark
30 January 2009 - Added information about use on K17, added information about other marks of 5.5" (14 cm) guns
29 February 2012 - Converted link to Wayback Archives