I use a piece of perforated steel. I pre bake to 140 degreed so the bullets are hot when I spray. Then I spray, turn up to 180 degrees and bake for 20 mins.
I use perforated steel because sometimes the bullets are stuck to the tray and they're easier to break off.
Apparently some people use a non-stick baking sheet but I don't really see how the earth connection is maintained.