Kills vs. Assists XP... and Assists Count as Kills

I have gotten 3 headshot markers after a vehicle drove past me full of enemies.

I sprayed the car but it just drove off. I don't know if there's a timer or what but after hitting 3 different people in the head i got no assists or any points at all.

Now if they would of gotten blown up in that vehicle straight after i hit them i probably would of got 3 assists but they survived and probably healed up.

I wonder how long it is before your dmg doesn't count anymore. If i snipe someone with a 2 shot per kill gun and only hit them once to the body, if that person lives for X amount of time afterwards then you don't get an assist or XP?

Mabye if they heal up to 100% then your dmg no longer counts.

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@Reddoguk wrote:

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Maybe if they heal up to 100% then your dmg no longer counts.

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THAT is your answer, right there!

Notice now if you get killed, you can see top right on the screen how much damage that you still carried around with you from previous enemies shooting/damaging you.  And how much each of them had of total % of health still inflicted on you.  But to OP's point @SterlingARCH3R , if you now die, then those still remaining/inflicted damage points should then be awarded to the originator accordingly as XP leading to your death!