Nope.
1. When bullet spawns, get owner of bullet (the player).
2. When bullet hits, store player it hit.
3. Send both info over to a score keeper, e.g. using the event info, set event data pair. Depending on mechanics, only when kill, every time etc.
Compute that data in the score keeper. Make yet another FSM that gets that data from score keeper, and updates the UIs.