LKk/42 (12.7 mm)

Description

The 12.7 mm LKk/42 was a Finnish copy of the 13.2 mm FN Browning aircraft machine gun from WWII. LKk/42 is an abbreviation for LentoKoneKivääri (an amalgamation of lentokone = aircraft, konekivääri = machine gun) m/42.

The Finnish managed to get the plans for the gun via Sweden as war aid in the early 1940s. The calibre was changed to 12.7 mm Browning and the weapon was used to upgrade old fighter aircraft such as Brewster Buffalos and Curtiss Hawk 75's in Finnish service during the later stages of the war.

The weapon has different belts and bullets compared to other guns firing the 12.7 mm Browning cartridge which are unique to Finland.

Vehicles equipped with this weapon

• ▄B-239
• VL Myrsky II
• VL Pyörremyrsky

General info

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Available ammunition

The 12.7 mm LKk/42 uses the American 12.7x99 Browning cartridge, modernly called .50 BMG. This round was produced in Finland but with domestic projectile types during WWII. These consist of 3 types: AP, AP-T, and Incendiary. Projectile performance is more or less equal to their American counterparts, however the overall efficiency of the gun is limited due to the lack of any API or API-T rounds.

• Default: AP-T · AP · I
• Universal: AP-T · AP-T · I
• Ground targets: AP-T · AP · AP-T · AP
• Air targets: AP-T · I · I · I
• Tracers: AP-T · AP-T · AP-T · AP-T
• Stealth: AP · I · AP · I

Comparison with analogues

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Usage in battles

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Pros and cons

Pros:

• High accuracy
• High velocity
• Reasonable fire rate (750 rpm when synchronized through a propeller)
• Ease of use (uses 12.7x99 ammo like the common M2 Browning found on countless other vehicles which simplifies the learning curve a lot)
• Viable penetration against lightly armoured vehicles

Cons:

• Limited to 3 ammunition types, AP, AP-T and Incendiary, all of Finnish origin.
• Lowered fire rate when synchronized through a propeller

History

Origin

Like most modern nations prior to WWII, the Finnish wanted to adopt a heavy airborne weapon which could deal with the armoured full metal fighters and bombers entering service at the end of the 1930s. There were several weapons on the market designed for this specific purpose and one of those was the 13.2 mm FN Browning aircraft machine gun by FN Herstal. The weapon had a high rate of fire at ca. 1,100 rounds per minute and could fire high explosive projectiles. This was the weapon Finland wanted to buy.

Unfortunately, Finland was not alone in wanting to buy the gun and several countries stood in line to buy it. Things only got worse as the Winter War started in September 1939 which meant that a suitable replacement had to be found quickly. In the end, the Finnish had to adopt the M2 Browning (export name Colt MG 53-2) as they ordered the Brewster Buffalo in December 1939.

Predecessor

The Finnish were never happy with the 12.7 mm Colt MG 53-2 as it was heavy and had an unimpressive fire rate of ca 750 rounds per minute even when not synchronized through a propeller. They also did not have a license to build the Colt MG 53-2 which meant that they would have to find a successor quickly as their entire air force was becoming outdated quickly. Because of this, when the winter war ended in March 1940, the Finnish were hoping to be able to buy the 13.2 mm FN Browning machine gun yet again. But to their dismay, Belgium was invaded by Nazi Germany just 2 months after the winter war had ended which meant that FN Herstal could not export weapons.

Source

Fortunately for Finland though, their neighbour and close friend Sweden had been first in line to buy the 13.2 mm FN Browning from FN Herstal and had acquired several guns and a license to produce them just as the invasion of Belgium started. This prompted Finland to ask Sweden in 1941 if they could get access to its plans as war aid. As FN Herstal was under occupation Sweden did not see any reason against giving Finland unauthorized access to the license plans and Sweden agreed to send over the plans they had. But to the horror of the Fins, the plans were incomplete, although this was not the fault of the Swedes as they had the same problem. Because of this, the Finnish asked the Swedish if they could send over an original gun to use as reference to complete the plans. The Swedish agreed and sent over a copy.

Design

Now came the problem of calibre. The original gun was in calibre 13.2x99 Hotchkiss, a calibre the Finnish did not use nor produce. Fortunately for them, FN Herstal had prior to the war offered the 13.2 mm FN Browning in not only 13.2 mm Hotchkiss but also 12.7 mm Browning, a cartridge the Finnish had in production due to the 12.7 mm Colt MG 53-2. Because of this, the Finnish decided to convert the gun to 12.7 mm Browning. The task of converting the construction to 12.7 mm, and making it capable of being produced in Finland was given to the Finnish state weapon factory VKT. VKT had to make a couple of hundred design changes to the weapon for it to be produced in Finland. One of these changes was to make it fit the same mounts as the MG 53-2.

Service

Initial use

The weapon was designated 12.70 mm LKk/42 and production started in 1942 with the first weapons being sent out to FAF wings in 1943. The 12.7 mm LKk/42 was mainly sent to wings using the Brewster Buffalo (designated BW in Finland) as they already had installations for them but the 12.7 mm LKk/42 also ended up in a few Curtiss Hawk 75's (designated CU in Finland) and Morane-Saulnier MS.406's (designated MS in Finland) as they were also in need of better weaponry.

Main use

Besides upgrading old planes the Finnish also planned to use the 12.7 mm LKk/42 on several future aircraft. One of these was the VL Myrsky, a single-engine monoplane fighter with a mixed construction airframe and 1,100 hp Twin Wasp engine. The Finnish had been working on the Myrsky since 1939, but because of the war they had not been able to acquire any engine for the aircraft. By 1943 the Finnish had finally been able to acquire enough engines to start production of the Myrsky. As the Myrsky was severely outdated as a fighter by 1943 it was decided to give it extremely heavy hitting armament so it could at least take down slow attack aircraft such as the IL-2 Sturmovik. The Myrsky ended up receiving four 12.7 mm LKk/42 machine guns in the nose, all shooting synchronized through the propeller. While this lowered the rate of fire of the 12.7 mm LKk/42 from ca. 1,100 rounds per minute to around 750 rounds per minute it was still heavy-hitting as all 4 machine guns sat next to each other and fired within a 1-metre span. This concentrated the fire and turned anything it hit into Swiss cheese within seconds. In the end however, the Myrsky only ever destroyed 2 aircraft (damaged 2 fighters which crashed on landing) and it was almost immediately relegated to reconnaissance and ground attack missions. This only got worse with time as its mixed construction did not fare well in the Finnish climate.

Planned use

Besides the Myrsky the 12.7 mm LKk/42 was also planned to be used on several future aircraft being developed in Finland. One of these was the VL Humu, a Brewster Buffalo clone using Soviet M-63 radial engines captured from I-16's. The Humu was to mount three synchronized 12.7 mm Lkk/42 guns in the upper cowling. The Humu was however underpowered and never passed its initial trials in 1944.

On the other end, we have the more famous VL Pyörremyrsky fighter. The Pyörremyrsky was effectively an improved Bf 109G-6 as it used the same engine and cowling as the Bf 109 G-6 yet was able to outperform it in both climb rate and manoeuvrability. The Finnish tried also tried to improve its armament. One of the limitations of the Bf 109 G-6 was its 13 mm MG 131 machine guns. The 13 mm MG 131, while firing fairly effective projectiles, had extremely lousy muzzle velocity. The 12.7 mm LKk/42 did not. The Finnish therefor planned to use 12.7 mm LKk/42 machine guns on the Pyörremyrsky instead of 13 mm MG 131's. This was however never realized as the continuation war ended in 1944 which nailed the coffin for the Pyörremyrsky.

Anti air use

After the war, most aircraft using the 12.7 mm LKk/42 reached the end of their service life quickly and by 1950 most 12.7 mm LKk/42's were in storage waiting for better days. As a lot of the guns were effectively brand new, not to mention indigenous, the Finnish military tried to figure ways to re-purpose them.

One of these ideas was to turn them into anti-air machine guns. The 12.7 mm LKk/42 was promptly put into service as an anti-air gun during the early 1950s. As an anti-air gun, the 12.7 mm LKk/42 was re-designated to 12.7 mm TorKk/42 VKT, TorKk being an abbreviation for TorjuntaKonekivääri (anti-air machine gun), although it was sometimes called 12.7 mm VKT-42.

The 12.7 mm TorKk/42 was fitted in single, double and quadruple mounts. In the end however, it failed as an anti-air gun. Because of its high rate of fire and thin barrel, it could not be used to full effect on the ground and was thus never successful in the anti-air role. A few seconds of fire could crack the barrels and make the gun unsafe for use. It was withdrawn from anti-air service after a short period in use during the early 1950s.

Exercise use

So the 12.7 mm LKk/42 was not viable as an anti-air gun. This forced the Finnish military to rethink what to do with the guns. For inspiration, they looked to their neighbour Sweden who originally gave them the design. Since Sweden also produced the base gun during the war they most likely were in a similar boat to Finland, which was true.

Sweden's solution to the problem however was to use the surplus weapons as exercise weaponry on all their 20 mm cannon equipped aircraft. This was done by replacing the 20 mm cannons with the surplus machine guns and therefore save money by using cheaper ammunition. Finland, who had just acquired six de Havilland Vampire fighters, liked the idea and decided to copy it. This proved to be a great idea in the long run and Finland continued to use the 12.7 mm LKk/42 for exercise use into the 1990s.

Media

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See also

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External links

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Aircraft machine guns
USA
7.62 mm	Browning · M134 Minigun
12.7 mm	GAU-19 · M2 Browning · M3 Browning
Germany
7.62 mm	MG3
7.92 mm	MG 15 · MG 17 · MG 81
12.7 mm	FN M3P
13 mm	MG 131
USSR
7.62 mm	DA · GShG-7.62 · PKT · PV-1 · ShKAS
12.7 mm	A-12.7 · Berezin UB · TKB-481 · YaK-B
Britain
7.62 mm	FN 60.30 · L8A1
7.7 mm	Browning · Lewis · Vickers E · Vickers K
Japan
7.7 mm	Te-1 · Type 89 · Type 89 'special' · Type 92 · Type 97 navy
7.92 mm	Type 1 · Type 98
12.7 mm	Ho-103 · Ho-104
13 mm	Type 2
13.2 mm	Type 3
China
12.7 mm	QJK99-12.7-1
Italy
7.7 mm	Breda-SAFAT · Lewis
7.92 mm	FN Browning
12.7 mm	Breda-SAFAT · FN M3M · Scotti
France
7.5 mm	Darne 1933 · Fabrique Nationale Mle 38 · FN Browning · MAC 1934 · MAC 1934T · Mle 33 · Mle 1923
7.62 mm	PKA
7.92 mm	FN-Browning M.36 No.3 · FN-Browning M.36 No.4
Sweden
7.7 mm	FN-Browning M.36 No.3
8 mm	Ksp m/22 · Ksp m/22 Fh · Ksp m/22 Fv · Ksp m/22-37 R
12.7 mm	Akan m/39A · Akan m/40 · Akan m/45 · LKk/42
13.2 mm	Akan m/39 · Akan m/39A