The Owen has a simple blowback design, firing from an open bolt. It was designed to be fired either from the shoulder or the hip. It is easily recognisable, owing to its unconventional appearance, including the top-mounted magazine, and the side-mounted sight required to allow the firer to aim past it. The placement of the magazine allows gravity to assist the magazine spring in pushing cartridges down to the breech, which improves feeding reliability. Another unusual feature is the separate compartment inside the receiver, which isolates the small-diameter bolt from its retracting handle by means of a small bulkhead. This prevents dirt and mud from jamming the bolt, and makes the Owen a highly reliable weapon. Foreign dirt entering the gun would collect at the back of the receiver, where it would drain out or be expelled through a small opening. When tested, the Owen gun was able to continue firing despite being dipped in mud and drenched with sand, while a Sten gun and a Thompson also tested stopped functioning at once. In jungle warfare, where both mud and sand were frequent problems, the Owen gun was highly regarded by the soldiers.