Started playing this again and started getting into shotgunning people. Shotguns are pretty useless at the start of the battle, but after about half an hour with all sorts of tunnels, walls, bunkers, trenches, all those nice places to hide and do some CQC then they become handheld hell sprayers. Aim at the torso and you are pretty much guaranteed to get an instant kill from 15-20 blocks away. If you're out in the open being shot at, crouch then fire at your feet twice to create an instant foxhole!