Shadow Warrior 2

You may have to start a new game for this but early on in the game there is a bounty board mission called 'Pest Control' using a single fire weapon like the Devolver or Point Five-O, quick aim and shoot at any of the rats when they are charging at you. If you aim and shoot fast enough the auto aim should put be putting your shots dead center of the head, which is the confirmed weak spot for these rats. If you're running out of rats and still don't the achievement just teleport back, abandon mission and start again.