Disadvantages
The weapon is more prone to fire when dropped, and the open mechanism is more subject to picking up dirt when in the ready position, and so may require an additional ejector door or similar mechanism to exclude dust and dirt. 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, making them harder to use as forward-firing weapons on tractor configuration fighter aircraft. Accuracy can suffer somewhat in an open-bolt design, but this is generally less of a concern in automatic weapons.
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