13,2x99 Hotchkiss history


#1

So im new on this forum and im fairly new to the ammunition history scene. For the last years ive done a lot of research about swedish military aircrafts and their armament. Since a lot of it is swedish has made finding info fairly easy for me as i live in Sweden. But when i got to the 13,2 mm automatkanon m/39 (13,2 mm FN m.1939) i stepped right into a wall. Not only is there a general lack of info on this weapon (or was until i made a wikipedia page dedicated to it) but there is a general lack of info on its ammunition, the 13,2x99 mm Hotchkiss. When doing research on it i found that a there was a lot of threads about it in this forum. Considering that there should be a lot of people here who knows the general history of this round and where it was produced and sold i thought why not create a thread about it.
So my knowledge is lacking a lot about this subject. As ive understood, the 13,2x99 was developed about the same time as the 13,2x96 Hotchkiss and it was mainly used for export? It was produced in a lot of countries and mainly used for anti air guns? The FN herstal company was the first ones to make a gun for it that was meant to be mounted on airplanes? That gun became the FN m.1939 and was only used in Sweden and romania? Ammunition during ww2 was only produced in Sweden and Italy? And thats about it.
I hope this thread can explain a lot of the mystery’s about this cartridge.


#2

#3

During WW2 Germany also made this ammunition (steel cased with a special HE proj. design) for likely French and Belgian guns they had captured.


#4

The 13.2 x 99 cartridge was designed in the 1920s by Hotchkiss for their heavy machine gun which was used in the AA role, most extensively by the Japanese Navy who called it the 13mm Type 93. The Italians made their own gun to fire this ammo, the Breda M31, and mounted it in a light armoured vehicle. FN made a version of the .50 Browning MG under licence in both aircraft (air-cooled) and AA (water-cooled) variants: the customer could choose between 12.7mm and 13.2mm calibre. Except for the small difference in calibre, the round was identical to the 12.7 x 99 (.50 BMG) so the two are easily confused. To reduce the chance of this, the case was later shortened by Hotchkiss to 96mm. During WW2, Germany modified the case again by shortening it to 93mm so it could take cannon-type explosive projectiles made for the MG 131.

Yes, I believe you are right that the FN 13.2mm Browning aircraft gun only saw service in Sweden and Romania, although the Japanese Navy also copied the big Browning aircraft gun, choosing the 13.2mm calibre they already had in service; this was known as the 13mm Type 3.

It’s worth remembering that before WW2 the 13.2x99 cartridge was far more common than the 12.7x99, being in service in many countries in three different types of gun; at this time, the .50 BMG was largely confined to the USA. WW2 changed all of that, and postwar the 13.2mm Brownings were mainly converted to 12.7x99 - it only needed a barrel swap.


#5

We also may remember about Polish production here.

Tony, the projectile used in the 13.2 was not the MG131 type. As you remember the MG131 used a separate driving band while the 13.2 had a unique design where the steel body of the projectile formed a thicker portion and engaged the rifling with the bare steel body. This actually could be the reason why the Germans had no (known) AP types in this caliber.

Left the 13mm MG131, right the 13.2mm Hotchkiss:
Zwischenablage


#6

Anyone have any data for the ap round btw? All the data i have is the velocity which is 820 m/s


#7

Tony, the projectile used in the 13.2 was not the MG131 type. As you remember the MG131 used a separate driving band while the 13.2 had a unique design where the steel body of the projectile formed a thicker portion and engaged the rifling with the bare steel body. This actually could be the reason why the Germans had no (known) AP types in this caliber.

Thanks for that correction! I should have checked the 13.2x93 HE in my collection more carefully…


#8

Also some swedish data i have says that the ap projectile had 12 mm pen on a 60 degree slope at 200 m


#9

Romania also produced this cartridge:


#10

Did they actually produce it? I thought they only had a handfull of 13,2 mm FN m.1939 guns which where replaced rather quikcly with the mg151.