QF Mark V (40 mm)

Description

The QF Mark V (40 mm) on the Battle (D14).

The 40 mm QF Mark V is a naval anti-aircraft twin mounting that consists of two water-cooled, British-produced Bofors 40 mm L/60 guns. The Bofors 40 mm L/60, also known as the "Bofors L/60", the "Bofors gun", or simply "the Bofors", was a highly successful Swedish anti-aircraft gun design of the interwar period and was widely used during the Second World War by both sides and in all theatres and remained in service long after the end of WWII.

Vehicles equipped with this weapon

• HMS Armada
• HMS Belfast
• HMS Daring
• HMS Diamond
• HMS Diana
• HMS Liverpool

General info

The QF Mark V has a barrel diameter of 40 mm and has a barrel length of 2.25 m. It has a magazine size of 4 rounds per gun and has a rate of fire of 156 rounds per minute, though firing for too long will jam the gun.

Available ammunition

Depending on the vehicle, there are up to three belts available. Note that Default and Universal refer to the same belt, depending on the vehicle.

• Default/Universal: AP-T · HEFI-T
• 40 mm HE clips: HEFI-T · HEFI-T · HEFI-T · AP-T
• 40 mm AP clips: AP-T · AP-T · AP-T · HEFI-T

Not all belts listed are available on all vehicles equipped with this weapon.

Penetration statistics
Ammunition	Penetration @ 0° Angle of Attack (mm)
	10 m	100 m	500 m	1,000 m	1,500 m	2,000 m
HEFI-T	3	3	3	3	3	3
AP-T	81	78	68	58	49	41

Shell details
Ammunition	Velocity (m/s)	Projectile mass (kg)	Fuse delay (m)	Fuse sensitivity (mm)	Explosive mass (TNT equivalent) (g)	Ricochet
						0%	50%	100%
HEFI-T	874	0.9	0	0.1	67.13	79°	80°	81°
AP-T	874	0.89	-	-	-	47°	60°	65°

Comparison with analogues

All naval Bofors 40 mm L60 guns are virtually identical, the only difference between them being the rate of fire: all single mounts fire at 160 rpm, while twin and quadruple mounts fire at 156 rpm. They all fire the same ammunition from 4-round ammunition clips and have a short enough reload that they can sustain continuous fire as if there wasn't a reload at all. In other words, their cyclic rate of fire (mechanical rate of fire) is the same as their effective rate of fire (rate of fire with reload times taken into account). All naval Bofors 40 mm L60 guns can jam if fired for too long.

The only naval Bofors 40 mm L/70 currently present in the game is the 40 mm MEL58, which is, by and large, superior with a much higher rate of fire of 240 rounds per minute. The only other difference is the HE round: the MEL58's HE round has less explosive mass (36.25 g TNTeq), but it has a higher muzzle velocity (1,030 m/s).

The 40 mm Bofors Flak 28 is the only naval Bofors gun in-game with access to a pure HE ammunition choice, at the cost of not having any AP options. Every other naval Bofors gun has ammunition choices comprised of a mix of HE and AP, in ratios of 1:1, 3:1, or 1:3.

Compared to other common guns of similar calibre:

• 3,7 cm SK C/30 (37 mm): The 3,7 cm SK C/30 has a higher muzzle velocity for both its AP and HE rounds (1,000 m/s) and has a stronger AP round (87 mm @ 10 m, 0°; 37,4 g TNTeq); but it has a much slower rate of fire (30 rpm), has a weaker HE round (274 g TNTeq), and has a lower projectile mass for both its AP round (820 g) and HE round (750 g). This gun is single-shot and cannot jam.

• 3,7 cm FlaK-Lafette C/36 (37 mm) and 3,7 cm FlaK-Lafette LM/42 (37 mm): These guns have a higher rate of fire (250 rpm), but they have a lower muzzle velocity for both their AP round (845 m/s) and HE round (815 m/s), have a weaker AP round (67 mm @ 10 m, 0°) and a weaker HE round (44.03 kg TNTeq), and have a lower projectile mass for both their AP round (700 g) and HE round (623 g). These guns fire from a 5-round ammunition clip and have a very quick reload, so their cyclic rate of fire and effective rate of fire are practically identical. They cannot jam.

• 70-K (37 mm): The 70-K has a higher muzzle velocity for its HE round (880 m/s); but it has has a lower rate of fire (150 rpm), has a lower muzzle velocity for its AP round (880 m/s), has a weaker AP round (79 mm @ 10 m, 0°) and a weaker HE round (0.05698 kg TNTeq), and has a lower projectile mass in both its AP round (0.758 kg) and HE round (0.72 kg). It fires from a 500-round magazine and can jam if fired for too long.

• 2pdr QF Mk.IIc (40 mm) and 2pdr QF Mk.VIII (40 mm): These guns have a higher rate of fire (200 rpm) and have a lower projectile mass in their AP round (910 g); but they have a lower muzzle velocity for its AP and HE rounds (701 m/s), have a weaker AP round (60 mm @ 10 m, 0°) and a weaker HE round (71 g TNTeq), and have a lower projectile mass in both their HE round (820 g). They fire from a 56 round magazine and cannot jam.

Usage in battles

A twin mount of one of the best medium-range anti-aircraft cannons in the game, the QF Mark V provides very good AA coverage for any ships that it's mounted on. With a 98.6 g TNTeq explosive charge in each HE round, any hit on an enemy aircraft will usually result in critical damage, if not a kill. The rounds that these guns fire have an above-average muzzle velocity and projectile mass, resulting in a much longer effective range than guns of similar calibre: laterally (i.e. targeting surface targets), the maximum range is about 3.25 km.

Despite each gun's small magazine size of only four rounds, the reload is short enough that there isn't any noticeable difference between its cyclic rate of fire (the rate of fire only considering the mechanical speed of the gun) and its effective rate of fire (the rate of fire accounting for reload times). In other words, they can sustain virtually continuous fire, as if there was no reloading at all. However, this comes at the cost that if fired for too long, the gun can jam. For this reason, it can be advantageous to set the AI gunners to only target aircraft. If allowed to target surface targets, the AI gunners will often waste ammunition on targets well outside of the gun's maximum range, leaving the guns jammed when actually needed.

Since the QF Mark V can currently only be found on destroyers and cruisers, if the choice is available, there is no reason to use any ammunition option other than 40 mm HE clips since it contains the highest ratio of HE to AP rounds. While the AP rounds do have a very gun penetration for its calibre, armoured targets are more effectively dealt with using the destroyer's main armament anyway. With the 40 mm HE clips, the QF Mark V will have the highest effectiveness against its intended targets, aircraft and small boats.

Pros and cons

Pros:

• Large explosive mass in HE round
• High-penetration AP round
• Very quick reload

Cons:

• Can jam if fired for too long

History

In 1928, the Swedish Royal Navy contracted the Bofors Company to design a suitable replacement for their Vickers 2-pounder guns anti-aircraft guns (the Vickers "Pom-Poms"). Work on the design began right away and a prototype model was produced by mid-1930. The prototype had a vertical sliding breech block design and was automatic. Upon firing, the recoil of the gun would open the breech and eject the spent casing out its rear whilst an autoloading mechanism would insert the next round into the empty breech, after which the action of the gun sliding back into place would close the breech once again, leaving the gun ready to fire once more.

While proving the potential of the design, the prototype failed to meet the specified rate of fire requirement of 130 rounds per minute. It wasn't until 1934 that a production model, 40 mm L/60 Model 1934, was ready. In the following years, minor improvements led to the development of 40 mm L/60 Model 1936, which would finally be accepted into Swedish service as 40 mm/60 Model 1936. Despite its name, the barrel length of the 40 mm L/60 Model 1936 was actually 2250 mm (56.25 calibres).

The British Army first purchased 100 Bofors guns in 1937 for examination and testing which were found to show satisfactory performance. However, many parts of the gun as originally designed were intended to be fashioned or fitted by hand, limiting the rate of production to a pace that couldn't possibly meet British demand. Thus, Britain acquired a licence to produce the gun domestically. Changes were made to the design to streamline mass production, including the conversion of measurements from metric to imperial. These changes not only vastly improved production efficiency, but they also lowered production costs.

The Mark V mounting was a twin mount design that used the American Mark 1 twin mount as a design base, making use of interchangeable parts from the existing gun mount designs where possible. The Mark V mount (designated R.P.50 Mark V) used two 40 mm Mark XI guns (designated "Ordnance, Quick Firing 40 mm Mark XI") fitted side-by-side, though many of these were actually 40 mm Mark IV or Mark IV/I guns converted to the Mark XI standard. The original air-cooled barrel of the Bofors L/60 would overheat after firing approximately 300 rounds and would need to be replaced to continue firing. The Mark XI was water-cooled to help alleviate this issue, and the Mark V mount had water tanks and pumps to circulate the coolant through the guns' water sleeves. In total, the Mark V mount weighed 6.5 tonnes.

Like its American counterpart, the Mark V used two mirrored versions of the Mark XI, one for each side. The turret could be aimed either remotely by a central fire control director located elsewhere on the ship, or by the gunner, seated to the left of the guns, who controlled the turret's R.P.50 metadyne electric drives with a joystick. In the case of electrical failure, the mount could also be aimed and fired manually by two crewmen seated on each side of the gun. The crewman on the right-hand side is the gun trainer, who traversed the mount horizontally by turning a crank, while the crewman on the left side, the gunlayer, elevated the guns in the same manner. The Mark V mount could elevate -15°/+90°, although this was changed to -14°/+90° post-WWII, and it could train and elevate at a rate of 35°/s and 28°/s, respectively.

SAP, AP, and HE rounds were produced for the British Bofors guns, each weighing 0.894 kg (1.97 lbs.). Both SAP and AP were painted black with white tips, with AP being distinguished by a white ring painted on the body. HE, painted buff, had 68 g (0.15 lbs.) of TNT and self-destroyed after travelling for approximately 3,200 m (3,500 yds). Rounds with tracer were indicated by an additional red ring. At the rear of the firing platform were two ready-use ammunition racks with a capacity for six clips each. Ammunition was loaded by the crew through the top of the guns into ammunition "hoppers", from which the automatic loaders pull the ammunition from. The gunlayer fires both guns with either a button on his joystick or manually through the use of foot pedals, with the guns being able to fire in single fire or automatic modes. Spent cartridges were ejected out of the rear of the gun, down chutes redirecting them under the guns towards the front where they can be ejected safely away from the crew.

The Mark V twin mount, commonly known as the "Utility" mount, entered service in February 1945. The Royal Navy estimated that the Bofors gun was about as effective against kamikaze aircraft as their domestic design, the Vickers 2-pdr Pom-Poms, but they found that the Bofors gun was about twice as effective against bombers. The Mark V mount replaced the Mark IV "Hazemeyer" twin mount and, after WWII, the STAAG Mark II twin mount, both of which were much more complex than the Mark V mount. Despite lacking many of the onboard central fire control systems that were present on the previous two mounts, the Mark V mount was liked for its simple design and reliability. Remaining in use well beyond the end of WWII, it's a testament to the gun's effectiveness as an anti-aircraft weapon that it remained in service for so long, hindered only by the arrival of the jet age.

Media

Excellent additions to the article would be video guides, screenshots from the game, and photos.

See also

Other variants of the Bofors 40 mm gun

• Bofors (40 mm) (Family)

Other British 40 mm naval guns

• 2pdr QF Mk.IIc (40 mm)

External links

• Historic Naval Ships Association - Handbook for 40 mm BOFORS Twin R.P. 50 Mark 5 Mounting - Originally Handbook for 40 mm BOFORS Twin R.P. 50 Mark 5 Mounting, Admiralty Naval Ordnance Department, 1950
• NavWeaps - USA Bofors 40 mm L/60 Model 1936
• [Wikipedia] Bofors 40 mm gun