Have not tried, pretty unique set of steps, but I imagine it would look like this:
1) player 1 with RAK in inventory one way or another tries to pull out the RAK and start shooting while crouched
2) Player 2 kills player 1
3) Player 2 checks the contents of player 1
I imagine I Must have just killed him at the perfect timing as he was firing the gun. so to the game it was in his hands, as he died went back into his inventory but was still firing on the frame that happened?