It seems that Black's 2 realistic options are either shooting at White or shooting into the air (shooting at Grey is not an option)
If he shoots into the air instead of at White then he increases his chances of surviving round one from 7/9 to 9/9 (100%), if the other guys behave logically.
Shooting at White and hitting him also means Grey will go first in a Black/Grey showdown which is bad and lengthen's Black's odds of survival.
So shooting into the air seems like maybe the better option on round 1 for Black.
It will increase the odds of facing White instead of Grey in the 2 man showdown once 1 player is dead, which seems bad, but it is maybe more than balanced out by reducing the odds of Grey going first in a possible Black/Grey showdown so I will guess shoot into the air.