New type of rivet?

[airguy]

I've seen quite a few pictures of screws without threads, and even run across a couple myself - but this is a first for me.

 

[HFS]

Gives "double flush" a whole new meaning ...

HFS

 

[docjjrmd]

I've seen quite a few pictures of screws without threads, and even run across a couple myself - but this is a first for me.

Used to ease disassembly of parts...

 

[bobrv7taildragger]

I've seen quite a few pictures of screws without threads, and even run across a couple myself - but this is a first for me.

 

[raabs]

It's a barrel rivet

 

[fixnflyguy]

Believe it or not, they exist in the industry. It's called a "slug rivet",usually used in automated riveting, though I'm sure your example just missed the forming die.