Japanese 13mm A/T rifle

General Ammunition Discussion
#1

On a recent visit to the Armouries in Leeds I came across this in a bound volume called the ‘Technical Intelligence Summary’. This item is from summary No54 and is dated September 20th, 1941.

13mm.jpg1005×686

I’ve had a look through Elks book on Japanese ammunition but there is no mention of anti-tank ammunition. Does anyone know if there was an indigenous Japanese anti-tank rifle as this article seems to suggest? Maybe it was something picked up in China and taken into service using existing captured ammunition?

Certainly a 25 round magazine for a 13mm rifle would be a bit of a beast (who has thumbs strong enough for the last couple of rounds?) and tricky to conceal except in the very longest grass.

Happy collecting, Peter

#2

Peter, this is a very interesting report. The only information I have about this rifle is found in two US reports dated May 20 and October 22, 1942.

The first describes the organization of Japanese parachute forces and its armament by September 1941:

  • Revolvers: 360
  • 6.5 mm machine carbines - 300
  • Heavy machine guns: 42
  • 13 mm Anti tank rifles: 55
  • Arisaka cannon: 9

This is the second report:

#3

I presume that the ammo was the standard 13.2x99 Hotchkiss as used by the IJN? They did of course describe their 13.2mm guns as 13mm, and 25mm maximum penetration would be about right, at short range against a vertical plate.

#4

Tony, reported projectile weight is too light for a 13.2 x 99 and total weight is excesive (c. 1000 grs more).

#5

Well, a different bullet could have been developed - but you are right about the total weight, it’s at least 50% heavier than my figures for the 13.2x99. It must use a much bigger cartridge case (why didn’t they measure the thing at the same times as weighing it?).

Surprising that Ken Elks missed it - he did a lot of research into his book.

#6

To say nothing of that “6.5 m/m machine carbine.” What do you suppose their source had been smoking? Jack

#7

Here’s the actual description of the May 20, 1942 report:

Later reports describes the Arisaka cannon as “40-mm Arisaka cannon (Model 19)”.

#8

That does indeed look rather odd.

The IJA used semi-auto pistols, not revolvers. As Jack said, I know of no “6.5mm machine carbine” or anything like it. Neither have I ever heard of a “40mm Arisaka cannon”. And what does it mean by “heavy machine gun”? If they mean 13mm, that was a navy weapon, not army.

#9

Is it possible this arm did not exist? Info on Japanese equipment prewar was limited. The USN built a class of battle cruisers to counter a believed but nonexistent IJN battle cruiser threat.

#10

Another description from a report dated December 2, 1942 (Organization of the Japanese parachute company (July 1941).

#11

There are a couple of videos about Japanese army airborne forces exercises c.1941-42 where I have found some images of the 20 mm Type 97 rifle in “action”:

#12

I am deeply sceptical about this whole report - none of it makes much sense.

It is puzzling, thought, to see such exact figures being given for the weight of the 13mm AT projectile and cartridge in that first extract.

#13

[quote=“Fede”]Peter, this is a very interesting report. The only information I have about this rifle is found in two US reports dated May 20 and October 22, 1942.

The first describes the organization of Japanese parachute forces and its armament by September 1941:

  • Revolvers: 360
  • 6.5 mm machine carbines - 300
  • Heavy machine guns: 42
  • 13 mm Anti tank rifles: 55
  • Arisaka cannon: 9

This is the second report:

[/quote]

If you compare this given weight of 1,55ounces to the first given grains in the first posting, than you see, that the first infomation must be wrong (as it didnt match the 1,55ounces given here in the second info), and that the whole cartridge weight is exactly 1000grs to much. Means, the whole cartridge has 122 to 128 grams, and the bullet as a 1.55ounces weight, equals to 54,67grams…and this data is full in the range of the weight specs for a normal 13,2 Hotchkiss round…Considering this, this socalled 13mm AT-Gun must be a Naval hotchkiss gun Type 93 with Magazin feed…The number of guns is also exact in the range of issued guns of this type to Navy Paratroopers…

And ALSO the other data about 6,5 SUBMACHINE GUN, isnt wrong. The Navy played INSIDE of Japan (not in the Battlefield) with a complete new cartridge of 6,5mm Pistol-Caliber design, which prooved unsatisfactory, as not having enough impact force…So the normal SUBMACHINE GUN at the frontline was still the 8mmSMG Typ 100. Here, also the number of guns issued (given with 300 guns) is correct…As soon I get the picture of this 6,5mm Cartridge, I will ask somebody to post it…

The socalled “heavy Machinegun” for the Navy is the Type 92 in 7,7mm…and also here, the number of issued guns (given as 42 pieces) is correct…
20mm guns where not isued in this high numbers to the troops…

The only completely wrong info is the info about Revolvers…Issued where 300 to 360 PISTOLs (in various calibers 7,65Brwng, 9mm Brwng and 8mm)

The info about a caliber .80 cannon isnt clear yet. A 50mm cannon is known…I will check on a 40mm cannon…but this takes time…
Have fun

Forensic

#14

First report indicates “weight of projectile” as being 680 grs (1.55428 oz / 44.0633 g) while the second report indicate it as being 1.55 oz (678.124 grs / 43.9417 g). I am missing something? Projectile weight is also too light if compared to reported 13.2 mm projectiles used by Japan.

If this 13 mm AT rifle round never existed we must admit that almost all data in the reports should be wrong (Type, Weight, Magazine capacity, Rate of fire, Weight of complete round & Type of mounting). Don’t take me wrong, I also believe this could be wrong anyway.

I didn’t notice that those “6.5-mm. machine carbines” could be reference to the 6.5 mm Model II submachine gun. This was tested by the Army in June 1937 in colaboration with Nambu Small Arms Company.

#15

If they do mean .80 (inch) caliber and not 80 caliber as stated (which could be the barrel length) then this is 20 mm. The army 20mm Type 98 automatic cannon (20x142) was stated to be dual-purpose: AA and AT.

What is the 50mm cannon?

#16

[quote=“Fede”]First report indicates “weight of projectile” as being 680 grs (1.55428 oz / 44.0633 g) while the second report indicate it as being 1.55 oz (678.124 grs / 43.9417 g). I am missing something? Projectile weight is also too light if compared to reported 13.2 mm projectiles used by Japan.

If this 13 mm AT rifle round never existed we must admit that almost all data in the reports should be wrong (Type, Weight, Magazine capacity, Rate of fire, Weight of complete round & Type of mounting). Don’t take me wrong, I also believe this could be wrong anyway.

I didn’t notice that those “6.5-mm. machine carbines” could be reference to the 6.5 mm Model II submachine gun. This was tested by the Army in June 1937 in colaboration with Nambu Small Arms Company.[/quote]

Fede,
Sorry, I calculated that last data by Troy ounces, which is given as 32,151 ounces per kilogram…which lets me come to 1000 metric gramms divided by this number 32,151 multiplied by 1,55 = 48,21 gramms…but if it is 1.55 ounce (av), than your calculation is correct for the bullet weight with 43,9417Gramms…(but maybe someone has backcalculated (av ounces to tr ounces, than he will end up at 680grs…)…but thats maybe my mistake, as i am not used to knew, what ounces are (TR) or are (AV)…

I just asked my friend TOKOI, who actually is on visit here…and he said, there was no other gun in 13mm, as the Mod.92…
and he confirmed, that the 6,5mm (SMG-Round) was also tested by Naval forces at home…
Anyway, he is now also interested, and will start his search to clarify this question…
All my best
Forensic

Tony, the info, that there was a 50mm cannon cames also from TOKOI, but he will check this. It was only in his mind, to have read something about that caliber in japanese papers…but maybe that was also only an experimental gun…But I will have his answer soon…
Your remark about .80 makes sense…
Forensic

#17

I’ve done a bit more digging on the bigger calibres:

The only 40mm cannon I know of in Japanese service in WW2 was the Ho-301 caseless Oerlikon-type Army aircraft gun. The Navy used to use the 40mm Vickers (2 pdr) but that was obsolescent by then.

I found one reference to a 5 cm cannon: a low-velocity Navy landing gun, probably obsolescent (actually Hotchkiss 47x136R ammo). There were also some Army 50mm grenade dischargers and a 50mm mortar.

#18

The Only other “13mm” AT specific cartridge at the relevant time which was still in use was the WW I “T-gewehr” cartridge, the 13x92SR; The Nationalist Chinese Army used it in old, WW I T-Gewehr ( an Upsized Mauser Action rifle);
Ammunition for the T-1918 was variously made by W+F Thun, and FN, up to the 1930s ( FN headstamps from the 1920s, and a Thun marked case from 1930, with the Nationalist “sunburst” as part of the HS.).

CHina would have certainly used these 13mm AT guns against the lightly armoured Japanese Tanks of the 1930s, and some (or many) would have been captured by the Japanese as well.
Whether the Japanese were experimenting with a similar 13mm gun, with a magazine, or even an early semi-auto 13mm version of the later (20mm) T97 gun, I cannot say. The Soviets also experimented with both the Cartridge and the TuF MG ( a large Maxim) into the mid-1920s, before going over to the 12,7 type cartridges, etc. Finally, Sweden adopted and made the T-Gewehr, as its M1921 Anti-Tank Rifle; and obviously also made ammo ( examples in Swedish Arms Museums.)

Finally, as can be seen from the numerous “Intel Reports” from both British and US (Military) observers of the 1920s and 30s, misinterpretations and outright mistakes are common, either from pure ignorance, or arrogance, and a failure to “back up” their reports with solid research. Even in the 1970s, it took a purely amateur source ( SOF) to get samples and extensive test reports on the then-new 5,45mm AK74 and its ammo. ( out of Afghanistan).

But then, the whole “13mm AT rifle” may be just another case of imcomplete or bad observation, or accepting some-else’s mistakes as fact…it happens too often to be dismissed.

Another mystery to unravel…and in an inscrutable language as well.

Regards,
Doc AV
AV Ballistics.

#19

Excellent narative. Gun experts are often not AMMO experts and many AMMO experts know little about the guns. Misinformation is frequently copied. The magazine capacity and firing rate which seems consistant through out the texts imply that this is all error related to the 20mm AT gun.

#20

I think this is the dual purpose 20mm Japanese cannon, as well as the wheeled mount it was also used on a tripod, I seem to recall it was known as the Model 38. It looks completely different to the weapon shewn by Fede in the still from the film on Japanese parachute troops.

japanese-20.jpg745×442

I’ll happily admit to knowing less than nothing on the subject so I may just be talking through my hat.

Happy collecting, Peter