For this part of the bounty it counts both kills and assists as part of the spread. What I would do is always stay close to one of your team mates and shoot at what ever they are shooting at. Play control, most of the fighting occurs at a flag so all you have to do is toss grenades in the general direction of the flag and can usually get assists at a minimum. Finally play early on the weekend mornings, competition seems to be lighter. I'm not the greatest in crucible but I noticed 8-10 am central time I would have had that spread in 2 games, versus when I did it, it took 5 games.