Unknown 28 cm shell case with Krupp number 830

[Hoeksel]

A friend shared attached pictures with me for my Krupp shell case publication. The shell case has Krupp number 830, Karlsruhe made, dated 1912 and measures ~ 285x688R315. It looks pretty unique to me as it is necked. I have no idea what this is.

 

[AKON_]

Hi Hoeksel ,I went through the sources about the k.u.k. and they are definitely not these :
28cm Küstenkanone (ca. 1882)
28cm Kanone L/35 (ca. 1905)
28cm Kanone L/35b (ca. 1905)
28cm Kanone L/35a (ca. 1905)
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Akon