Mystery Item, Cover No 2?

I have this mystery metal cover of some sort that, according to the vendor, came from Latvia. I wondered if anyone could positively identify exactly what it is, please?

Many thanks for any help and advice.

They look like covers for shell casings that are separate from their shells. Not sure steel would be used for this though.

Thanks for the suggestion. It could be almost anything.

it's about the size as a cigarette ash can outside the barracks - kept half full of sand. They had lids to keep the rain out of the sand when not in use.