I found a really easy way to do this was the same method for Running Man (don't try to get both in one game, you will void Running Man). Basically, around the 3:30 mark, you will have 5 enemies following you. Wait for them to be near an explosive tank and shoot at them. Hopefully you will detonate the tank along with all the enemies unlocking this achievement. It pops as soon as you get a quad kill.