It is not the 100 kills, it is the deaths that take away from it. 5 points for every kill - 2 points for every death. If someone is not good in PVP like me, 386 kills to 536 deaths. It makes this weapon tough to get. But that being said I do not have this bounty yet and it might be the last one I go for. Also I think a fusion rifle would be the best bet, second would be to snipe all the time. I say a fusion rifle as it has a high mag and reloads faster.