Pointy brass thing

[Icewing]

I found this a few days ago in a now empty lot, but can't make heads or tails of what it might have been. It's got threads both on the outside rim, and the inside of the cone.

 

[Tpmetal]

Why does it remind me of some sort of artillery fuse part? any chance of that?

 

[DCMatt]

Possibly part of a soda-acid fire extinguisher?