6pdr 7cwt QF Mk IIA (57 mm)
Contents
Description
The Mark IIA was a modification of the army's Mark II anti-tank gun fitted with Molins auto-loading gear. Used by many MTBs in power operated mountings to give them a bigger "punch" when attacking barges and small vessels. It was also proposed to use the Mark II without the auto-loading gear as a wet mount for submarines but this never made it out of the prototype stage.
The Molins auto-loading gear carried seven rounds, one in the breech and six in the feed system. An additional twelve rounds were carried in ready racks on the naval mounting. The last round could not be fired, a precautionary measure to prevent the feed from running out of ammunition which would have necessitated manually working the breech mechanism.
Unlike the RAF version, this weapon allowed only semi-automatic firing.
These guns were of monobloc construction and actual bore length was 42.87 calibers. About 600 guns were produced with Molins gear.
Vehicles equipped with this weapon
General info
| Type | Fixed |
|---|---|
| Weight of Complete Round | 12.25 lbs. (5.56 kg) |
| Projectile Types and Weights | HE 1: 6.0 lbs. (2.72 kg) |
| Bursting Charge | N/A |
| Projectile Length | N/A
Complete Round: up to 24.85 in (63.1 cm) |
| Propellant Charge | 1.31 lbs. (0.59 kg) NF 029 |
| Muzzle Velocity | 2,150 fps (655 mps) 2 |
| Working Pressure | 20.5 tons/in2 (3,230 kg/cm2) |
| Approximate Barrel Life | 4,000 rounds |
| Ammunition stowage per gun | 7 rounds in gun and feed mechanism
12 ready rounds on mount |
- ^Only HE rounds were carried by MTBs.
- ^The muzzle velocity given above is for a Mark IIA gun firing 6 lbs. (2.72 kg) HE shell. The Mark II anti-tank gun firing 6.28 lbs. (2.85 kg) AP shell had a MV of 2,845 fps (867 mps).
| Designation | 6-pdr / 7cwt QF Mark IIA |
|---|---|
| Ship Class Used On | MTBs |
| Date Of Design | 1940 (naval version) |
| Date In Service | 1941 |
| Gun Weight | 760 lbs. (345 kg) |
| Gun Length oa | 101 in (2.564 m) |
| Bore Length | 96.2 in (2.444 m) |
| Rifling Length | 78.2 in (1.986 m) |
| Grooves | (24) 0.02 in deep x 0.22 in (0.51 mm x 5.59 mm) |
| Lands | 0.0737 in (1.872 mm) |
| Twist | Uniform RH 1 in 30 |
| Chamber Volume | 100 in3 (1.693 dm3) |
| Rate Of Fire | 40 rounds per minute cyclic18 rounds per minute practical |
Available ammunition
Describe the shells that are available for the weapon and their features and purpose. If it concerns autocannons or machine guns, write about different ammo belts and what is inside (which types of shells).
Comparison with analogues
Range with 6.0 lbs. (2.72 kg) HEElevationDistance12 degrees6,200 yards (5,670 m)
Usage in battles
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Pros and cons
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Pros:
Cons:
History
The 6-pounder 7-centum-weight Mark IIA is a variant of the British Army's 6-pounder Mark II. While the 6-pounder gun was a common naval calibre of the time, the British Army only began considering the design in 1938 when they realized their QF 2-pounders were likely to become obsolete soon after entering service. Due to the loss of British Army equipment during the evacuation at Dunkirk in June 1940, the development and the introduction of the 6-pounder were delayed with it only entering service in 1942. The Mark II, the main variant of the design, had an L/43 barrel. The Mark IIA combined this army cannon with the automatic loading system of the Molins Class M aircraft cannon to provide more firepower on Motor Torpedo Boats such as the Fairmile D against German barges and similar small vessels.
The Mk IIA had seven rounds in the auto-loading system: six rounds in the feed system, and one in the chamber. However, the gun, which was semi-automatic unlike the Molins, could only fire six rounds. The last round was left un-fired to prevent the breech from being worked manually which would be needed if the feed system was empty. A wet mount variant without the auto-loader was developed but remained a prototype.
Media
Excellent additions to the article would be video guides, screenshots from the game, and photos.
See also
- 6pdr OQF Mk.III (57 mm) - Tank version of the Mark II.
- 6pdr OQF Mk.V (57 mm) - Tank version with a longer barrel.
External links
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- topic on the official game forum;
- other literature.
