Nana guns are improvised bolt-action shotguns which feed from gravity magazines. They are no more complex than a collection of springs, tubes and sheet metal arranged somewhat logically. After each shot, the user must cock back the charging handle, which will allow another shell to fall into the chamber. Beware leaving the bolt open, as the magazine may empty itself on the ground. Because these weapons do not have the strongest action, most of them are chambered in the lighter-shooting 20-gauge.