WWII Japanese large ammo help

I bought these 2 together, they appear to be the same caliber, but the 2nd one has being cut down for some purpose. The longer round measures 25x140mm approximately. It also has an irregular groove running the entire circumference right above the ejector groove. What is this round and why there is an irregular groove?

These are 3 shots of the longer round, I rolled it 3 times to show how irregular the extra groove is.

I would say these are crude trench art pieces as both casings have been altered. The irregular groove appears to be cut with a file in an ill fated attempt to either decorate the case or cut it down just above the case head. There are many examples of trench art pieces around made from Japanese cases and I suspect this is because of the many soldiers, marines and sailors in the Pacific during WW2 creating trinkets for back home.


These look like Japanese 25x163 Hotchkiss AA cases which got their projectiles cut off as the crimps on them are too heavy to just bent them out as so many people like to do.