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.
3"/40 13cwt gun on Trawler during World
12-pdr [3"/40 (76.2 cm)] 12cwt QF HA Marks I, II and V
|Ship Class Used On||British
27-knot destroyers of the 1890s, World War I destroyers, RFAs and DEMs 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)|
(see Note 1)
|Uniform RH 1 in 30|
|Chamber Volume||121.7 in3 (1.994 dm3)|
|Rate Of Fire||15 rounds per minute|
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.
|Type||British and Japanese: Separate
|Projectile Types and Weights||British
HE - 12.9 lbs. (5.87 kg)
|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
2,235 fps (681 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.|
|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)|
|Designation||British 12cwt Mounting
PI and PI*
HA VIII and HA VIII*
HA/LA IX, HA/LA IX* and HA/LA IX**
|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)
PI*: -10 / +30 degrees
HA VIII: -10 / +90 degrees
HA/LA IX: -10 / +70 degrees
|Elevation Rate||Manually operated, only|
|Train Rate||Manually operated, only|
|Gun recoil||9.6 - 10 in (24 - 25 cm)|
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.
21 November 2006 - Benchmark
29 August 2011 - Corrected typographical error
15 December 2013 - Added Additional Pictures Page