Judging by the length , shape & the two grooved driving bands , I suspect this Rocket assisted projectile is for the s. 10,5cm Kanone 35 (t)
The thread could very well be 48mm wide & not M50 x 3 , however that wouldn’t necessarily be the deciding factor in this case. But would be nice to know.
Attached some images to show what I mean. One is a close-up of the driving bands , the other the thread & then the German documents on the 10,5cm Granate 35 (t) variants. I’m unable to read the length of the projectiles mentioned properly but if I read it correctly , it says something like 540mm including fuze. So the length is definitely not far off , if any.
Skoda developed more things like this so it would make sense.
Now all that’s left is to find a document in which this is mentioned.
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