WW1 German 155mm case ID?

[HoldThePickle24]

Hi gang, any thoughts on what this case might be? A buddy recently picked it up. About 211mm tall and 158ish at the mouth. Is it a cut down 15cm case?? The rim is thinner and squared (not rounded) compared to a 15cm K16 case. Your thoughts?

 

[Alpini]

Hi,

you are not the first person asking for this case here. I already answered the same question her: https://www.bocn.co.uk/threads/15cm-unknown-cartridge-case.103152/#post-316124

For whatever reason these German made cases had primer holes for Russian primers. Your case has an steel adapter to fit a standard German Schlagzündschraube 14.