Start Lifetime: Random between two constants: [0.2, 0.4]
Stop Action: Callback
Emission
Rate over Time: 0
Rate over Distance: 0
Bursts: 3 at time 0.
However, it seem the particle system only dies after 3 seconds.
I can see it from both the callback being called in delay, and when playing the particle system in the editor.
Ooop, never mind. I misread your post. You say you ARE getting the callback, just a lot later than you would intuit it should happen based on your timings?