Mitrailleuse d'Avion Browning - F.N. Calibre 13,2 mm

Browning Aircraft Machine Gun - F.N. Caliber 13.2 mm (French: Mitrailleuse d'Avion Browning - F.N. Calibre 13,2 mm), more commonly known as the 13.2 mm FN Browning,[6] but also 13.2 mm Browning-F.N.[2] or FN Browning M.1939, was a 13.2 mm (0.52 in) caliber, shell-firing, heavy machine gun for aircraft use,[2][1] designed by Fabrique Nationale (F.N.) in Herstal, Belgium, as a private export venture during the final years prior to World War II.[2]

Mitrailleuse d'Avion Browning - F.N. Calibre 13,2 mm
13.2 mm FN Browning
Swedish 13.2 mm automatkanon m/39A
TypeAircraft ordnance:
1. – machine gun[1]
2. – shell-firing gun[2]
3. – autocannon[3]
Place of origin Belgium
Service history
In serviceSwedish Air Force
1939–1957: frontline[4]
1951–2007: exercise[5]
Used by Sweden
 Romania
 Finland
WarsWorld War II
Production history
Designed1938
ManufacturerFN Herstal
L.M.E
Produced1939-ca 1946
Variants13,2 mm Browning-F.N.
13,2 mm akan m/39
13,2 mm akan m/39A
12,7 mm akan m/39
12,7 mm akan m/39A
12,7 mm VKT 12,70 LKk/42
Specifications
MassCannon weight: 24.3 kg (54 lb)
Barrel weight: 3.3 kg (7.3 lb)
Link weight: 0.017 kg (0.037 lb)
Length1,415 mm (55.7 in)
(1,450 mm (57 in) with flash hider)
Barrel length816.5 mm (32.15 in)
(919 mm (36.2 in) with flash hider)
Cartridge(Original)
13.2 x 99 Hotchkiss
(Patron m/39 in the SAF)
(Later)
12.7 x 99 Browning
(Patron m/45 in the SAF)
Cartridge weighton average 120 g (0.26 lb) (13.2 x 99 Hotchkiss)
Caliber13.2 mm (0.52 in) (original)
12.7 mm (0.50 in) (later)
BarrelsThe barrel had eight constantly rising grooves going right.
400 mm (16 in)/revolution
Groove depth was 0.16 mm (0.0063 in)
ActionElectrical
Rate of fire1 080 rpm (standard)
600 rpm (lowest)
1 500 rpm (highest)
Muzzle velocity810–900 m/s (13.2 x 99 Hotchkiss)
Effective firing rangeTracer to 1,000 m (1,100 yd)
Maximum firing rangeca 7,000 m (7,700 yd)
Feed systemBelt fed (able to feed from both left and right)
SightsReflexsikte m/37 (Saab 18 & 21)
Reflexsikte m/42B (FFVS J 22)
Gyroreflexsikte K-14 (Saab 21A-3)
References

Development

The weapon was originally based on the M2 Browning but was heavily modified with a high rate of fire and the ability to fire high-explosive bullets, just designed, for the FN Browning.[1] The cartridge used was the 13.2 x 99 mm Hotchkiss round, based on the 13.2 x 99 mm ammunition originally designed for use in the Hotchkiss M1929 machine gun. While basically a machine gun, the invention of exploding bullets in this caliber allows this weapon to be called a "cannon" when firing such ammunition.[3] Normally, the smallest size explosive rounds in general use start at 20 mm.[2]

Due to the above-mentioned improvements the gun drew a lot of interest from a number of nations when it entered the export market in 1939.[2] With the start of WW2, and the subsequent invasion and occupation of Belgium in the summer of 1940, the 13.2 mm FN Browning was, in that limited time, only exported to Romania[6] and Sweden.[7]

Export

Romania

The few weapons that were sold to Romania were at first used on their SM.79 bombers but later saw use on their own indigenous IAR 80B fighter plane. In Romania the weapons saw combat and were considered equal to the 20 mm weapons used in the Romanian air force such as the MG 151/20.

Sweden

In Sweden the weapon became their main aircraft weapon of WW2, playing a similar role to what the M2 Browning did for the Americans during WW2 where basically all US warplanes were armed with it as their main armament. While they never saw combat, they remained in use for an extended period.[3]

The weapons were later re-chambered as well, since Sweden adopted the 12.7 mm M2 Browning after WW2 when they bought surplus P-51D's. Since 12.7 mm ammunition was cheaper to buy than the cost to produce new 13.2 mm ammunition, all 13.2 mm weapons were re-chambered during the post-war era, and after 1950 basically all Swedish weapons fired the new cartridge. Even though the 12.7 mm cartridge was considered a downgrade it did not matter as Sweden's main fighter fleet had by then been upgraded to Vampire fighter planes armed with 20 mm cannons.[8]

In Sweden the weapon got the designation 13,2 mm automatkanon m/39, abbreviated as 13,2 mm akan m/39, meaning 13.2 mm (0.52 in) autocannon m/39 and was later produced by Ericsson as the 13,2 mm akan m/39A.[3]

Variants

  • 13,2 mm akan m/39 – Original Browning FN weapons built in Belgium
  • 13,2 mm akan m/39A – Weapons built by Ericsson in Sweden

Finland

Finland never formally got the chance to buy the Belgian design before the invasion of Belgium, however through their connections with Sweden they managed to get hold of the manufacturing blueprints for the weapon which allowed them to produce it in Finland.[7][9] Since Finland already was producing 12.7 × 99 mm BMG ammunition it was decided to produce the weapon chambered for that cartridge.[7][9] The Finnish variant was produced by the Finnish State Rifle Factory Valtion Kivääritehdas (VKT) and received the designation 12,70 mm LentoKoneKivääri m/42, abbreviated as 12,70 LKk/42, meaning 12.7 mm (0.50 in) air machine gun m/42.[7][9]

In Finland the weapon was used to rearm many of Finland's fighter aircraft as many of them were older pre-war designs armed with weak or unreliable weapons. The LKk/42 guns were mainly fitted to Finnish Curtiss 75 Hawk[10] and Brewster B-239 Buffalo[11] planes, but also to the indigenous Finnish VL Myrsky fighter aircraft.[11] The weapon was also planned to be used on the VL Humu and VL Pyörremyrsky fighter aircraft if they were to enter production.

After WWII the Finnish would use the 12,70 LKk/42 as training weaponry in aircraft such as the Saab 35 Draken and BAE Hawk.[11]

References

Footnotes
  1. "XII. Les munitions F.N. calibre 13,2 mm". La mitrailleuse Browning FN (in French). Belgium: Fabrique Nationale Herstal. 1939. pp. 24, 25.
  2. King, H. F. (1939-12-21). "A Survey of the armament of single seat fighters". Flight. December 21, 1939: 505–509.
  3. Söderberg, N.; Björkstand, N. (1949). Beskrivning över 12,7 mm akan m/39, 12,7 mm akan m/45, 13,2 mm akan m/39, 13,2 mm akan m/39A, 1949 års upplaga (in Swedish) (1955 ed.). Stockholm, Sweden: Royal Swedish Air Force Materiel Administration, Kungliga boktryckeriet, P. A. Norstedt & Söner.
  4. Henricson, A.; Malmberg, E. (1957). Flygvapnets eldvapenammunition, fastställd 1957 (in Swedish) (1961 ed.). Stockholm, Sweden: Royal Swedish Air Force Materiel Administration publishing section.
  5. AMKAT, Ammunitionskatalog, Data och bilder, Gemensam (in Swedish) (2007 ed.). Stockholm, Sweden: Defence Materiel Administration. 2001.
  6. Brînzan, Radu (2014). Vânător – Romanian Hunter, The I.A.R.80 and I.A.R.81 in Ultimate Detail. Mushroom Model Publications. p. 285. ISBN 9788363678401.
  7. Thorsson, Nils (1975). Historik och kartläggning av vapenmateriel för flygplan. Arboga, Sweden. pp. 0–14.
  8. "Vampire in Sweden".
  9. Ford, Dan (2014-05-01). "Browning machine gun?". tapatalk.com. Archived from the original on 2018-01-23. Retrieved 2021-11-18.
  10. Keskinen, Kalevi; Stenman, Kari; Niska, Klaus (1975). Suomen Ilmavoimien Historia 05, Curtiss Hawk 75 A, P-40M (in Finnish). Finland: Tietoteos. p. 6. ISBN 951-9035-22-2.
  11. Kolju, Panu (May 2019). "Finnish-built Brownings for the Buffalo". warbirdforum.com. Archived from the original on 2021-11-18. Retrieved 2021-11-18.

Printed sources
  • "XII. Les munitions F.N. calibre 13,2 mm". La mitrailleuse Browning FN (in French). Belgium: Fabrique Nationale Herstal. 1939. pp. 24, 25.
  • Brînzan, Radu (2014). Vânător – Romanian Hunter, The I.A.R.80 and I.A.R.81 in Ultimate Detail. Mushroom Model Publications. p. 285. ISBN 9788363678401.
  • Källqvist, Lennart; Norrbohm, Gösta; Skogsberg, Bertil; Karlström, Björn (1986). Det bevingade verket, Svensk militär flygteknik och materiel under 50 år (in Swedish). Försvarets materielverk, Huvudavdelningen för flygmateriel. Stockholm, Sweden: Försvarets materielverk, Huvudavdelningen för flygmateriel. p. 32. ISBN 9178105439.
  • Thunberg, L.; Björkstrand, N. (1948). Flygvapnets eldvapenammunition, fastställd 1948 (in Swedish) (1949 ed.). Stockholm, Sweden: Royal Swedish Air Force Materiel Administration & Victor Pettersons Bokindustriaktiebolag Stockholm.
  • Söderberg, N.; Björkstand, N. (1949). Beskrivning över 12,7 mm akan m/39, 12,7 mm akan m/45, 13,2 mm akan m/39, 13,2 mm akan m/39A, 1949 års upplaga (in Swedish) (1955 ed.). Stockholm, Sweden: Royal Swedish Air Force Materiel Administration, Kungliga boktryckeriet, P. A. Norstedt & Söner.
  • Thorsson, Nils (1975). Historik och kartläggning av vapenmateriel för flygplan. Arboga, Sweden. pp. 0–14.

Web sources
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