Unidentified brass object

I am hoping someone might be able to help me.
I have attached pictures of a brass object long held in our family. We are from Maitland NSW Australia
The family story is that the object had something to do with the war. There was a munitions factory in Rutherford in WWII so we always thought it had something to do with that. Lots of experts are telling me it is not ordinance related. But no one can suggest what else it could be. I would appreciate any suggestions. It could be part of a tank as the factory had a hull shop.
There are no markings on it. It weighs 2.2 kg, is 7cm high and is 14cm in diameter
Kind Regards

 

Could it be an early stage of drawing or forming a shell case?

 

Were any of your ancestors engineers, especially ships' engineers, or foundry craftsmen? As part of their training they were tested on fabricating strange shapes of about that size, sometimes of no particular use, although sometimes finished into poker stands or door stops.

 

Possibly a small persons protective helmet

 

It could be a bowl similar to this:
Vintage M.M.S.- Mobile Minesweeper Ship- WWII BRITISH Royal Navy BRASS BOWL~1940 | #3822579014

 

I have seen similar brass scale pans. The heavy ones were machined to a specific constant weight and shape/size to avoid recalibration. These tend to have some kind of validation stamp.
Otherwise, I'd go with a billet for a stamping, pressing or drawing process.

 

During her shift at the ammo factory, Mabel made an ashtray for her mother.

 

Mould for a mkIII helmet?

 

It has been hammered and knocked about on the outside and graduated on the inner curves. I'd suspect some sort of former or gauge...I'm not sure why bronze or brass though. Most finished products would have been marked - "DD" in Australia. I'm inclined to think tooling or measuring rather than a finished object. Bronze was widely used in explosives factories where a spark from steel would have been fatal. In the absence of factory tooling blueprints, it's probably going to remain as speculation. Sadly, we've waited too long to ask these questions.

 

No, no one in the family like that at the time