Compared to a closed-bolt design, open-bolt weapons generally have fewer moving parts. The firing pin is often part of the bolt, saving on manufacturing costs; the inertia of the bolt closing also causes the fixed firing pin to strike a blow on the primer, without need for a separate hammer/striker and spring. In automatic weapons an open bolt helps eliminate the dangerous phenomenon known as "cook-off", wherein the firing chamber becomes so hot that rounds spontaneously fire without trigger input, continuing to fire until the ammunition is exhausted. Open-bolt designs typically operate much cooler than closed-bolt designs due to the airflow allowed into the chamber, action and barrel during pauses between bursts, making them more suitable for constant full-automatic weapons such as machine guns.
The weapon is more prone to fire when dropped and some open-bolt designs can suffer from a condition in which bolt retention fails and the weapon discharges even with no trigger input. Open-bolt machine guns could not be synchronized to fire through the arc of a propeller due to the relatively long period between sear disengagement and the ignition of the cartridge, making them harder to use as forward-firing weapons on tractor configuration fighter aircraft. Accuracy can suffer somewhat in an open-bolt design, again due to the longer delay between pulling the trigger and primer ignition, but this is generally less of a concern in automatic weapons, since after the first shot, the operation is indistinguishable from a firearm that fires from a closed bolt. It is only when the trigger is released that the bolt is caught in the rearward position; during automatic fire, both types of bolts are free to operate at full rate, without hindrance. As most open-bolt guns are automatics, generally only weapons, such as submachine guns, converted to semi-automatic operation suffer from this.
Since the weapon must be carried with the bolt open in order to fire, this leaves the breech and action internals open to dirt and dust contamination through the open ejection port, unless some sort of cover can be devised. Some versions of the open-bolt M3 submachine gun utilized a hinged sheet metal ejection port cover that doubled as a safety; when closed, it both covered the ejection port and blocked the bolt from closing. When ready to fire, the user simply flipped the cover down, opening the ejection port and unblocking the bolt.
An open-bolt weapon will typically have a higher rate of fire than a comparable closed-bolt weapon; the bolt simply needs to return forwards in order for the weapon to fire again, while a closed-bolt design has the additional step of the hammer striking the firing pin. Having a higher fire rate can be both an advantage and disadvantage depending on the situation. For handheld weapons, typically a lower rate of fire is desirable, as this will conserve ammunition and help keep the level of recoil more manageable. For vehicle-mounted weapons or fixed emplacements, however, a higher rate of fire is often desirable. In these situations, ammunition and recoil are less of a concern and the higher rate of fire will increase the likelihood of a round hitting the target, particularly when employed against fast-moving targets such as aircraft.
Many movies and video games portray open-bolt weapons as needing to be cycled after reloading. This is not generally true, however, as open-bolt weapons send the bolt carrier back into a cocked position via the excess gas after the last round is fired. The exception to this is if the weapon is fully automatic and the trigger is held down after the last round was fired (and the gun does not have a 'last round bolt hold open' mechanism) at which point the bolt will fly forward once more and stay there. In this case, the bolt merely needs to be retracted to the rearward position and does not return forward as is sometimes portrayed.