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

Mitrailleuse d´Avion Browning - F.N. Calibre 13,2 mm
Automatkanon m/39
Type	Heavy machine gun in Romania Autocannon in Sweden
Place of origin	Belgium
Service history
In service	1939-1957 Swedish air force (used as training weapons on the Saab 29 to 37)
Used by	Sweden  Romania
Wars	World war II
Production history
Designed	1938
Manufacturer	FN Herstal L.M.E
Produced	1939-ca 1946
Variants	13,2 mm FN M.1939 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
Weight	Cannon weight: 24.3 kg (54 lb) Barrel weight: 3.3 kg (7.3 lb) Link weight: 0.017 kg (0.037 lb)
Length	1,415 mm (55.7 in) (1,450 mm (57 in) with flash hider)
Barrel length	816.5 mm (32.15 in) (919 mm (36.2 in) with flash hider)
Cartridge	(Original) 13.2x99 Hotchkiss (Patron m/39 in the SAF) (Later) 12.7x99 Browning (Patron m/45 in the SAF)
Cartridge weight	on average 120 gr (0.017 lb) (13.2x99 Hotchkiss)
Caliber	13.2 mm (0.52 in) (original) 12.7 mm (0.50 in) (later)
Barrels	The barrel had eight constantly rising grooves going right. 400 mm (16 in)/revolution Groove depth was 0.16 mm (0.0063 in)
Action	Electrical
Rate of fire	1 080 rpm (standard) 600 rpm (lowest) 1 500 rpm (highest)
Muzzle velocity	810–900 m/s (13.2x99 Hotchkiss)
Effective firing range	Tracer to 1,000 m (1,100 yd)
Maximum firing range	ca 7,000 m (7,700 yd)
Feed system	Belt fed (able to feed from both left and right)
Sights	Reflexsikte m/37 (Saab 18 & 21) Reflexsikte m/42B (FFVS J 22) Gyroreflexsikte K-14 (Saab 21A-3)
References

The Mitrailleuse d´Avion Browning - F.N. Calibre 13,2 mm, more commonly known as the FN Browning M.1939 or the Browning FN (as a nickname) was a heavy airplane machine gun built for export the year prior to WW2 by Fabrique Nationale "FN herstal" in Belgium.

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 Browning FN. The cartridge used on the weapon was the 13,2x99 Hotchkiss round, originally designed for use in the Hotchkiss M1929 machine gun. This cartridge had almost double the energy of the 12,7 mm round used on the M2 Browning.

Due to the above-mentioned improvements the gun got a lot of interest from a lot of nations when it entered the export market in 1939. Due to the start of WW2 and the invasion of Belgium it was only exported to Romania and Sweden. Sweden was able to buy the majority of the weapons and even got the blueprints to produce the weapon on their own without paying for a license. In Sweden the weapon got the designation Automatkanon m/39, short Akan m/39, meaning Autocannon m/39 and was later produced by Ericsson as the Akan m/39A. Sweden also gave the blueprints to Finland so they could also produce the weapon. Since Finland was already producing 12,7 mm ammunition the Finnish variant was rechambered to 12,7 mm. The Finnish variant was designated VKT 12,70 LKk/42 and was produced by the state of Finland.

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 ingenious 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.

Finland

In Finland the weapon were used to up arm a lot of Finlands fighter planes as a lot of them were on the brink of becoming obsolete. They were mainly used on their P-36 Hawk planes and their ingenious VL Myrsky.

Sweden

In Sweden the weapon became their main aircraft weapon of WW2, playing a similar role to what the M2 Browning did to the Americans during WW2 where basically all warplanes was armed with it as their main armament. The weapons were later rechambered to 12,7 mm since Sweden adopted the M2 Browning after WW2 when they bought surpluss P-51D's. Since the 12,7 mm ammunition were cheaper to buy than to produce new 13,2 mm ammunition all 13,2 mm weapons were rechambered during a longer time and after 1950 basically all weapons fired the new cartridge. Even though the 12,7 mm cartridge was considered a downgrade it didn't matter as Swedens main fighter force had been upgraded to Vampire fighter planes armed with 20 mm cannons.

Variants

• Automatkanon m/39, Akan m/39 - Original Browning FN weapons built in Belgium.
• Automatkanon m/39A, Akan m/39A - Weapons built by Ericsson in Sweden.

References