To earn this achievement, you must rip Mr.Dismount limb by limb, with no body parts connected to each other. You could do it in every map possible but the easiest map to earn this map
https://steamcommunity.com/sharedfiles/filedetails/?id=26834... (WARNING: IF YOU PLAY ON A LOW END PC, TURN YOUR GRAPHICS SETTINGS DOWN. THIS WILL CAUSE LAG). It might take a few tries, this will increase your chances more than the default maps.