FN 32 Auto Fibre? projectile

Headstamp F N *

What is it?
I first thought it was simply an oxidised lead projectile until I looked closer and it felt too light.

edit to reduce picture size.

It is a blank. They exist in at least 9 mm Browning Long, 9 mm Court (.380 Auto), 7.65 mm Browning, and 635 mm Auto.