Shadowrun Returns

Like a lot of the other kill based achievements in this game, this can be easily acquired by saving before killing enemies with ARs and then reloading the save until they are dead enough times. Kills from runners you hire do count for this, it doesn't have to be your char specifically. ARs are quite powerful weapons, with a long effective range and the capability to do burst/full auto fire with less than half investment into their skill. There is no penalty (that I noticed) for carrying a heavier weapon, so I recommend that you carry one in your characters loadout, as they are very useful. Samurai class runners are your best bet if you aren't carrying one yourself, as for the most part, the more "specialist" classes will carry pistols or SMGs instead. You can check a runners gear in the hire screen to check their guns, if you want to hire someone for this.