Japanese ww2 'adiabatic' fuzes for 20mm shells

[msxyz]

Somehow, I suspected it because all the drawings I've seen of 'air column' fuzes have a straight or slightly tapered channel and not such a big hollow space behind the nose

 

[SaparotRob]

So I looked up what adiabatic means and I found this:

 

[msxyz]

Speaking about odd japanese fuzes, what about the one used by the army Ma 202 round for the Ho-5 cannon? According to the descriptions I've seen, it's a brass capsule filled with plain PETN (Not mixed with wax or any insensible explosives) that should explode when crushed. Is it even safe? PETN is also sensible to extreme shocks. Wouldn't it explode also while being accelerated out of the gun barrel?

 

[A.G. Williams]

Wouldn't it explode also while being accelerated out of the gun barrel?

It appears that it didn't.

I wouldn't care to test one by dropping it onto a hard floor, though...