Left 4 dead 2: Gnome achievement

The  "Guardin' Gnome" achievment can be only obtained during the Dark Carnival campaign in Left 4 Dead 2.

he can be picked up by scoring over 750 points in the shooting gallery minigame at The Fairgrounds and must be taken all the way to the rescue zone.

This can be pretty hard to do so I recommend doing it with friends, since you can't shoot while you have the gnome, but at least you can still push zombies. It should be easy to do while playing with friends.

You are definetely not going to be able to do this while playing alone, if you have no friends to do this with, it can still be achieved with random players if there as long as there is communication between the members.