7.7X58SR Arisaka Explosive


#1

Thought some of you might be interested in this sectioned 7.7X58 Arisaka Explosive bullet. I related my story of sectioning this in an eariler thead, but just briefly, I was young, stupid, and DAMN lucky. Had no idea what this bullet was back in 1960 when I sectioned it with a steel file. Folks, in case you don’t know that white powder is RDX and PETN explosive. I have never seen one of these fired, but I am sure it would have removed my fingers or my hand or possibly my head had it gone off. Anybody out there have any idea just how big of an explosion these make? Anyway, I did it so you don’t have to to see the construction.


#2

Scary, Ron. That’s one round that I won’t section; apparently, the “fuze” mechanism is simply nitroglycerine-soaked paper (I’m guessing that’s what’s inside the capsule at the rear), and it could go off anytime during manufacture, loading handling, or firing. It must’ve been approved by the same ordnance genius that approved the Type 94 pistol with the exposed sear.


#3

SDC–No Nitroglycerin involved. The gray at the rear is a lead slug. When the bullet hits, the lead slug crushes the RDX in the part just in front of it which is pressure and shock sensitive which then sets off the PETN main charge in the nose.


#4

That’s a new one on me; everything I’ve read on these makes mention of the fact that they weren’t “bore-safe”, and this was supposedly because the “nitroglycerine” would come out of suspension when they were fired. If it was an impact fuze that required the base core to move forward, I wouldn’t expect them to go off if dropped (which apparently happened the first few times US troops encountered these things).


#5

Nothing to do with the cartridge, but just a point. While I agree that the Type 94 represents the nadir of pistol design, the highly respected (not by me) Luger Pistol, a jamming wonder with poor sights, although very accurate for those that can get by the horrible trigger pulls, also has an exposed sear. When the gun is partially disassembled, and the top half is off of the gun, if there is a round in the chamber the gun can be accidentally fired in exactly the same way as the Japanese Type 94. that is why for a time, in the 1920s, the P-08 was equipped for police with a sear safety and on some, that and a magazine safety, due to accidents by police officers. Of course I would take a Luger over any Japanese pistol design, but not many guns are perfect! By the way, I said I didn’t respect the luger - I have had many of them and it is like a Single Action Colt - there is something about them that captures the imagination of gun enthusiasts, including me. Well, sorry I got off the point of the thread.


#6

Ron,
How does this 7.7X58 Arisaka Explosive bullet look in its native unfired state? Would you happen to have a photo? I’d like to memorize it just in case I am lucky (or not) to bump into one.


#7

Here you go, Vlad . . . note the blunt nose which is perfectly flat across, perhaps 1/8" in diameter.

.


#8

Vlad–They can be recognized by the flat meplat instead of a pointed bullet. The meplat is about 1/10 inch across. They have a purple casemouth seal…Ball has a pink CM, AP is black, tracer is green and incendiary is magenta. BTW, the official Japanese designation for the Explosive round was “Incendiary Ma 101”. Also, I have been remiss in the discussion so far in not noting that the explosive is a Type 92 cartridge which is semi-rimmed, not rimless. I have edited the name of this thread to correct this miss-naming.


#9

Here are two slightly different variations of the semi rimmed HE and a CN jacketed HE projectile in a 7.7 rimmed cartridge (.303)


#10

This same load and flat-tip bullet was used in 7.9 x 57mm by Japan, also.


#11

Some years ago we test fired various explosive/incendiary rounds against steel plates at 50 metres. I reloaded the bullets into my .308 x 1,5" cases.

We tested the .303 BVI, .303 BVII, Russian red tip explosive, Russian API and Japanese 7.7 explosive among others. There was very little to choose between them in terms of visual effect, although the Japanese was probably the most spectacular, but it had little effect on the plate.

Regards
TonyE


#12

Just to ad to the thread. BEM used to correspond with John Green of Tasmania by snail mail. He told me that one time at a show a hippy looking fellow walked up th him and pulled an 7.7x58 explosive cartridge out off his pocket and asked John if he wanted to buy it. When John asked him where he got it he said oh I have this whole pocket full of them! To prevent a disaster John bought them all.


#13

[quote=“TonyE”]Some years ago we test fired various explosive/incendiary rounds against steel plates at 50 metres. I reloaded the bullets into my .308 x 1,5" cases.

We tested the .303 BVI, .303 BVII, Russian red tip explosive, Russian API and Japanese 7.7 explosive among others. There was very little to choose between them in terms of visual effect, although the Japanese was probably the most spectacular, but it had little effect on the plate.

Regards
TonyE[/quote]

I would be interested to hear how you managed to pull the Japanese ones.


#14

This is how they look coming out of the 15 round packet.


#15

[quote=“CSAEOD”][quote=“TonyE”]Some years ago we test fired various explosive/incendiary rounds against steel plates at 50 metres. I reloaded the bullets into my .308 x 1,5" cases.

We tested the .303 BVI, .303 BVII, Russian red tip explosive, Russian API and Japanese 7.7 explosive among others. There was very little to choose between them in terms of visual effect, although the Japanese was probably the most spectacular, but it had little effect on the plate.

Regards
TonyE[/quote]

I would be interested to hear how you managed to pull the Japanese ones.[/quote]

We used a collet puller in a loading press that grips the bullet just above the neck of the case.

Regards
TonyE


#16

From my dark recollections, Explosives Inspector “Mac” McGaw, (Qld) once destroyed over ten thousand of these Flat tipped rounds in one sitting at the Explosives Reserve range (back in the 1960s). They had come in as scrap metal from one of the Pacific Islands Airstrips (some islands’ main economy is scrap metal collection from WW II).
Mac had been an ordnance tech during the latter years of WW II, in the Pacific, and when he switched to a public service job with the Mines Department post-war, he was “the” expert in “bringback” souvenirs from the Pacific War, American, Aussie and Japanese.

Elks, in his treatise on Japanese ammo, shows several variations of the “HE” type bullet, with the two jacket versions (common in the 12,7x81 SR cannon round) and the “percussion” version, as used in the smaller calibres (which also used the double jacket type as well. The Double jacket version replaced the more intricate Fused (Breda) HE-I used by the Japanese in 12,7 ( and 13,2mm) in the early part of the war

Later in the war, Picric Acid was used instead of RDX/PETN, and these were “bore sensitive”.

The Japanese Naval Type 87/92 7,7x56R ( aka .303) also had an explosive bullet variant…much used in New Guinea Postwar…it would punch a large hole in a Palm tree (or a neighbouring (enemy) tribesman.)

Regards, Doc AV
AV Ballistics.


#17

Was the Japanese 7.7 HE projectile ever fitted to the rimless cartridge?
Or was it fitted to the semi rimmed and rimmed only?


#18

Old thread I know.

According to a WWII military Man. I read. The 7.7 was supposed to make a 1 inch hole in aircraft alummium. I have two in my collection… one rimmed the other semi-rimmed.

Steve