This weapon was a Vickers design based on the British 2-pdr. Mark VIII but used on single and twin mountings similar to those used for the British 2-pdr. Mark II mountings. About 500 guns and 200 mountings were imported from Britain from 1925 to 1935. Used a 50 round belt although an unsuccessful attempt was made to increase this to 100 rounds.
Like all British 2-pdr. guns, this weapon had a low muzzle velocity and a short effective range. For that reason, these guns were replaced on most warships starting in 1935 by the Hotchkiss 25 mm gun.
Although this weapon was classified by the Japanese as being 62 calibers long, this dimension was actually the overall length of the weapon. True bore length of all British 2-pdr guns was 39.37 calibers.
|Designation||Vickers 40 mm/62 "HI" Shiki|
|Ship Class Used On||Many ships 1925 to 1935|
|Date Of Design||about 1923|
|Date In Service||1925|
|Gun Weight||619.5 lbs. (281 kg) including cooling water|
|Gun Length oa||98.5 in (2.502 m)|
|Bore Length||62.0 in (1.575 m)|
|Rifling Length||54.84 in (1.293 m)|
|Grooves||(12) 0.0141 in deep x 0.322 (0.358 x 8.18 mm)|
|Length Of Rifling||54.84 in (1.293 m)|
|Twist||Uniform RH 1 in 30|
|Chamber Volume||9.98 in3 (0.165 dm3)|
|Rate Of Fire||200 rounds per minute cyclical
60 - 100 rounds per minute practical
|Weight of Complete Round||HE 1
: 2.95 lbs. (1.34 kg)
SAP: 2.95 lbs. (1.34 kg)
|Projectile Types and Weights||HE: 2.0 lbs. (0.9 kg) 2
SAP: 2.0 lbs. (0.9 kg)
|Bursting Charge||HE: 0.16 lbs. (0.071 kg)
SAP: 0.05 lbs. (0.023 kg)
Complete round: 11.995 in (30.47 cm)
|Propellant Charge||HE: 0.243 lbs. (0.11 kg)
Cartridge weighed 2.9 lbs. (1.3 kg)
|Cartridge||40 x 158R|
|Muzzle Velocity||HE: 1,969 fps (600 mps)
|Working Pressure||15.5 tons / in2 (2,440 kg / cm2)|
|Approximate Barrel Life||5,000 rounds|
|Ammunition stowage per gun||N/A|
- ^The Japanese did not use the British 2-pdr. HE HV projectile, their HE projectile was equivalent to the British LV projectile.
Breakdown of HE shell weight Empty body 1.45 lbs. (0.66 kg) Driving band 0.875 oz (0.025 kg) Paint 0.125 oz (0.0035 kg) Bursting charge 2.5 oz (0.071 kg) Fuze No 131 5.25 oz (0.15 kg) Total filled 2 lbs. (0.9 kg)
- "Big Gun Monitors: The History of the Design, Construction and Operation of the Royal Navy's Monitors" by Ian Buxton
- "Naval Weapons of World War Two" by John Campbell
- "World War II Fact Files: Anti-Aircraft Guns" by Peter Chamberlain and Terry Gander
- "Japanese Cruisers of the Pacific War" by Eric Lacroix and Linton Wells II
- "Anatomy of the Ship: The Heavy Cruiser Takao" by Janusz Skulski"
- "Q.F. High Explosive 2 pdr Mark II N Shell - Forged Steel with Fixing Screw. Design." No. 21,071.c.(1) / A.D.G.S/3/164 dated 24 February 1916
Special help from Anthony G. Williams and Paul Roome