Britain
12-pdr [3"/40 (7.62 cm)] 12cwt QF Marks I, II and V
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Japan
3"/40 (7.62 cm) Elswick Pattern N and Vickers Mark Z
3"/40 (7.62 cm) 41st Year Type
8 cm/40 (3") 41st Year Type
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Italy
3"/40 (7.62 cm) Armstrong 1916 and 1917
76.2 mm/40 (3") Ansaldo 1916 and 1917
Updated 15 December 2013
First used on the "27-knot" destroyers of the 1890s.  Many small warships still carried these old guns during World War II and they were also used in coastal defense batteries.

The Mark I was a fairly complicated design of A tube, B tube, jacket and C hoop shrunk over the B tube/jacket join.  The Mark II was a First World War gun with a combined B tube and jacket while the Mark V was produced during the Second World War and had a monobloc barrel.  Some 4,737 Mark I and IIs were built along with an additional 3,494 Mark Vs.  Canada also built over 1,000 of these weapons, which were referred to as the "Ogden 3-inch" as they were manufactured at the Canadian Pacific Railway's Ogden shops in Calgary.

The Japanese guns were originally purchased directly from Elswick and Vickers but later ones were license-built copies.  These guns were similar to or virtually identical to the British Mark I.  Used as anti-torpedo boat guns on larger warships.  Redesignated as 41st Year Type on 25 December 1908.  Redesignated in centimeters on 5 October 1917.  Although finally classified as 8 cm, the bore remained 3.0" (7.62 cm).

Early Italian guns were purchased from Elswick.  Nearly all of the later ones were built by Ansaldo under license to a design provided by Armstrong during World War I or to a modified design for anti-aircraft mountings.  After World War I, these guns were used afloat mainly on older warships and auxiliaries.  About 730 guns were used for the anti-aircraft defense of Italy during World War II.

The data that follows is for the British version except where noted.
WNBR_3-40_mk1_Trawler_pic.jpg

3"/40 13cwt gun on Trawler during World War II
Note that the 2nd loader is holding only the cartridge while the round being rammed has a projectile.  This shows that this particular weapon fired separate ammunition.
IWM Photograph A 17177
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Click here for additional pictures
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Gun Characteristics
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Designation British
   12-pdr [3"/40 (76.2 cm)] 12cwt QF HA Marks I, II and V

Japanese
   3"/40 (7.62 cm) Elswick Pattern N and Vickers Mark Z
   3"/40 (7.62 cm) 41st Year Type (Model 1908)
   8 cm/40 (3") 41st Year Type (Model 1908)

Italian
   3"/40 (7.62 cm) Armstrong 1916 and 1917
   76.2 mm/40 (3") Ansaldo 1916 and 1917
Ship Class Used On British
   27-knot destroyers of the 1890s, World War I destroyers, RFAs and DEMs of World War II

Japanese
   Most warships built between 1890 and 1920

Italian
   Minor warships and auxiliaries of World War II
Date Of Design about 1893
Date In Service 1894
Gun Weight 0.6 tons (510 kg)
Gun Length oa 123.6 in (3.139 m)
Bore Length 120.0 in (3.048 m)
Rifling Length 103.0 in (2.617 m)
Grooves (16) 0.0375 in deep x 0.365 (0.953 x 9.27 mm)
Lands 0.224 in (5.69 mm)
Twist
(see Note 1)		 Uniform RH 1 in 30
Chamber Volume 121.7 in3 (1.994 dm3)
Rate Of Fire 15 rounds per minute
Notes:

1) The twist in some older guns either started at 1 in 120 increasing to 1 in 28 at the muzzle or were straight for the first 18 in (45.7 cm) and then increasing to 1 in 30 at the muzzle.

2) The Mark AV designation indicated guns that were fired by a lanyard rather than palm firing.
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Ammunition
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Type British and Japanese:  Separate
Italian:  Fixed
Projectile Types and Weights British
   HE - 12.9 lbs. (5.87 kg)

Japanese
   HE - 12.5 lbs. (5.67 kg)

Italian
   HE - 14.3 lbs. (6.5 kg)
   AA - 13.3 lbs. (6.0 kg)
Bursting Charge N/A
Projectile Length N/A
Propellant Charge 2.09 lbs. (0.95 kg) SC061 or 2.75 lbs. (1.25 kg) NF059

Cartridge:  Up to 9.5 lbs. (4.3 kg) with propellant
Muzzle Velocity British
   2,235 fps (681 mps)

Japanese
   2,231 fps (680 mps)

Italian
   HE - 2,231 fps (680 mps)
   AA - 2,264 fps (690 mps)
Working Pressure 16 in2 (2,520 kg/cm2)
Approximate Barrel Life 2,700 rounds
Ammunition stowage per gun N/A
Note:  Outfits for most British ships were SAP, CP, HE, shrapnel and star shell.  Submarine outfits were HE and star shell.  Flashless charges were supplied late during World War II.
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Range
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Elevation British with 12.9 lbs. (5.87 kg) HE Shell
Range @ 40 degrees 11,750 yards (10,740 m)
AA Range @ 70 degrees 19,000 feet (5,790 m)
Elevation Italian with 14.3 lbs. (6.5 kg) HE Shell
Range @ +42 degrees 10,940 yards (10,000 m)
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Mount / Turret Data
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Designation British 12cwt Mounting
   PI and PI*
   HA VIII and HA VIII*
   HA/LA IX, HA/LA IX* and HA/LA IX**

Japanese
   N/A

Italian
   Pedestal type
   RM1916 (Ansaldo)
   Ansaldo 1917
Weight  PI*:  1.233 tons (1,253 kg)
HA VIII:  2.10 tons (2,134 kg)
HA/LA IX:  2.45 tons (2,489 kg)
Elevation British
   PI*:  -10 / +30 degrees
   HA VIII:  -10 / +90 degrees
   HA/LA IX:  -10 / +70 degrees

Japanese
   Pedestal Type:  N/A

Italian
   Pedestal type:  -10 / +42 degrees
   RM1916 (Ansaldo):  -10 / +65 degrees
   Ansaldo 1917:  -10 / +75 degrees
Elevation Rate Manually operated, only
Train 360 degrees
Train Rate Manually operated, only
Gun recoil 9.6 - 10 in (24 - 25 cm)
Notes:

1) These guns were originally trained by the gunlayer's body weight against a training bar although elevation was controlled by a handwheel.

2) Most HA VIII mountings were later modified to use a hand wheel for training and redesignated HA VIII*.

3) Some PI mountings were modified to allow gunlayer firing, being redesignated as HA/LA IX* for Mark IA and IIA guns while HA/LA IX** were for Mark V and AV guns.
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Data from
"Naval Weapons of World War Two" and "The Battle of Tsu-Shima" articles in "Warship Volume II" all by John Campbell
Page History

21 November 2006 - Benchmark
29 August 2011 - Corrected typographical error
15 December 2013 - Added Additional Pictures Page