47mm projectile, but what?

[Tmine35]

I got this picture from my mate who is asking what this can be. Projectile body is polished brass and driving band copper. There are no markings at all. At nose cone is a kind of seam, so there may be a core inside.

 

[Tmine35]

Received some additional information: The nose cone has thread and turns off. Body is hollow inside and looks like being cast. Base is about 6-7mm thick.

 

[Gspragge]

These brass projectiles usually turn out to be decorative rather than
issue no matter where and when. Other than drill rounds and certain
projectiles for drill there seems no reason for all brass construction.