QF Mark V (40 mm)

40 mm QF Mark V

Information

Automatic CannonType

Britain County of Origin

General Characteristics

40 mmDiameter

2.25 mLength

4 roundsBelt Capacity

156 rpmRate of Fire

881 m/sMuzzle Velocity

80 mmMax Penetration

Production History

War OfficeDesigner

Full ProductionProduction Status

1940 - 1945Produced

Description

The QF Mark V is a naval twin anti-aircraft 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 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.

Other variants of the Bofors 40 mm gun within the game include:

• Bofors L/60 Mark 1: US-produced, water-cooled twin mount
• Bofors L/60 Mark 2: US-produced, water-cooled quad mount
• Bofors L/60 Mark 3: US-produced single mount
• 4 cm Bofors Flak 28: German captured single mount
• QF Mark VII: British-produced single mount
• QF STAAG Mark II: British-produced, water-cooled, and radar-guided twin mount
• Bofors (40 mm): Army version, mounted on various US and British anti-aircraft vehicles (SPAA)
• M266: Bofors 40 mm L/70 (increased barrel length and rate of fire), mounted on M247 Sergeant York

Vehicles equipped with this weapon

• HMS Armada
• HMS Belfast

General info

Each gun of the two guns in the QF Mark V has a barrel diameter of 40 mm and has a barrel length of 2.25 m. They have a magazine size of 4 rounds per gun and have a rate of fire of 156 rounds per minute per gun, 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
HEF-I	_	_	_	_	_	_
AP-T	80	77	66	57	50	45

Shell Details
Ammunition	Projectile Mass (kg)	Velocity (m/s)	Explosive Type	Explosive Mass (kg)	TNT Equivalent (kg)	Fuse Delay (m)	Fuse Sensitivity (mm)	Normalization at 30°	Ricochet
									0%	50%	100%
HEF-I	0.9	881	Tetryl	0.068	0.0986	0.0	0.1	_°	_°	_°	_°
AP-T	0.882	874	N/A	N/A	N/A	N/A	N/A	_°	_°	_°	_°

Tetryl is equivalent to 1.45x TNT.

Comparison with analogues

All naval Bofors 40 mm guns are virtually identical, the only difference between them being the number of guns in their respective mounts. They all fire the same ammunition from 4-round ammunition clips and have a short enough reload that they can sustain virtually continuous fire. In other words, their cyclic rate of fire (mechanical rate of fire) is practically the same as their effective rate of fire (rate of fire with reload times taken into account). All naval Bofors 40 mm guns can jam if fired for too long.

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 (1000 m/s) and has a stronger AP round (87 mm @ 10 m, 0°; 0.0374 kg TNT equivalence); but it has a much slower rate of fire (30 rpm), has a weaker HE round (0.0274 kg TNT equivalence), and has a lower projectile mass for both its AP round (0.82 kg) and HE round (0.75 kg). 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 (0.04403 kg TNT equivalent), and have a lower projectile mass for both their AP round (0.7 kg) and HE round (0.623 kg). 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 TNT equivalence), 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 (0.91 kg); 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 (0.071 kg TNT equivalence), and have a lower projectile mass in both their HE round (0.82 kg). 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 0.0986 kg TNT equivalent 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 the highest penetration compared to other similar guns, armoured targets can more effectively be dealt with using the destroyer or cruisers main armament.

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 breach and eject the spent casing out its rear whilst an autoloading mechanism would insert the next round into the empty breach, after which the action of the gun sliding back into place would close the breach 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 using the US Mark 1 twin mount as a base, interchanging parts from existing gun mount designs where possible. The Mark V mount (designated "RP50 Mark V") featured two Mark XI guns (designated "Ordnance, Quick Firing 40 mm Mark XI") fitted side-by-side, though many of these were actually 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 mid-battle 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. The Mark V mount, like many other Bofors gun mounts, was also designed to sync with a central fire control system. In total, the Mark V mount weighed 6.5 tonnes. It could elevate -15°/+90°, although this was changed to -14°/+90° post-WWII, and could traverse horizontally and vertically at a rate of 35°/s and 28°/s, respectively.

Like its American counterpart, the Mark V used two mirrored versions of the Mark XI, one for each side. These were trained by two crewmen, one on each side of the twin guns each with their own spider gun sight. The crewman on the right was the gun trainer who traversed the gun horizontally by rotating a crank, while the one on the left was the gun layer who traversed the gun vertically in the same manner and who also fired the gun, which he did through by pressing a foot pedal. Ammunition for the Bofors gun came in 4-round stripper clips, with both HE and AP clips available. At the rear of the Mark V mount were two small ammunition racks that could each hold six clips. Ammunition was loaded by the other crewmen through the top of each gun into the guns' automatic loaders, which would automatically strip the rounds from the clip. After firing, spent casings were ejected out the rear and guided down chutes directed towards the front of the guns where they could safely be flung away from the crew, all whilst the automatic loader fed in the next round.

The Mark V mount, commonly known as the "Utility" mount, entered service in early 1945, replacing the much more complex Mark IV twin mount. The Royal navy estimated that the Bofors gun was about twice as effective as the Vickers 2-pdr Pom-Poms against bombers, though against kamikaze aircraft, they were estimated to have about the same effectiveness. Nevertheless, the Mark V mounts were well-liked by their crew and remained in service long after the end of WWII.

Media

An excellent addition to the article would be a video guide, as well as screenshots from the game and photos.

See also

• QF Mark VII (40 mm)
• QF STAAG Mark II (40 mm)
• Bofors L/60 Mark 1 (40 mm)
• 2pdr QF Mk.IIc (40 mm)

External links

• NavWeaps - USA Bofors 40 mm L/60 Model 1936
• Wikipedia - Bofors 40 mm gun