Easy "Bounty Hunter" Achievement
Keep your eye on the scoreboard, as it will show the streaks that each player is on. As soon as you see someone is at a 15 streak, focus on killing them. It may be frustrating to just focus on getting this achievement, so just work on every other achievement while you're playing. In 250 hours you'll probably manage to kill someone on a 15 streak just by playing the game, so this one shouldn't be too hard.