Other Characteristics
Many movies and video games portray open-bolt weapons as needing to be charged after reloading. This is not generally true however, as the operation of basic open bolt weapons sends the bolt carrier back into a cocked position via the excess gas from the spent round. The sole exception is if the trigger was held down after the last round has been fired, at which point the bolt will fly forward once more and stay there. In this case, the bolt merely needs to be retracted, and does not go forward as is sometimes portrayed.
Another feature of open-bolt designs is that the magazine simply needs to be removed to completely unload the weapon. A closed bolt requires the second step of cycling the action to remove the last round in the chamber. It is essential to remove a loaded magazine before performing maintenance, or trying to cycle or close the bolt (as is often done to keep the weapon clean when not in use). If one were to close the bolt (say by pulling the trigger and riding the bolt to the closed position), as soon as the bolt closes it will fire if a loaded magazine was left in the gun.
Read more about this topic: Open Bolt