This achievement is a whole lot more tedious than it should be, the main way of doing this was to use vehicles in game modes that had them, however absolutely nobody plays them anymore, so the best way to currently do this is to get the kills using the RCXD Scorestreak as you can acquire it in normal multiplayer games, it will take a while to get all the kills this way, but it is a lot more consistent than trying to find games in modes with actual vehicles. If you can somehow find a game of combined arms(or have a team to boost with), the fastest method is to use the Helicopter that is in some of the maps and blow absolutely everyone up until you unlock the achievement.