The Owen gun, known officially as the Owen machine carbine, was an Australian submachine gun designed by Evelyn Owen in 1938. The Owen was the only entirely Australian-designed and constructed service submachine gun of World War II and was used by the Australian Army from 1942 until 1971.

The first prototype of the Owen gun was developed by Evelyn Owen in 1931, who finalised the design in 1938, when he was around 23.^[4] Owen submitted the design to the Australian military, but was rejected, as they were waiting for the British Sten to finish development.^[5] By May 1940, Owen had enlisted in the Second Australian Imperial Force, and was set to deploy to the Middle East, but after speaking about his design to the manager of a local plant of Lysaght, who had an interest in the design, Owen was transferred to the Central Inventions Board.^[4] In June 1941, Owen was discharged from the army and began to manufacture the Owen gun. After conducting tests in September that year, the Owen was found to be more accurate and reliable than competing designs such as the Sten and Thompson.^[4]

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.^[11] 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. The top-mounted magazine meant that if mud entered the weapon, it would either fall out on its own, or be pushed out by the magazine spring.^[12] 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.^[13] In jungle warfare, where both mud and sand were frequent problems, the Owen gun was highly regarded by the soldiers.^[14]

To facilitate cleaning, the ejector was built into the magazine, rather than the body of the gun. This allowed the barrel to be removed rapidly, by pulling up a spring-loaded plunger in front of the magazine housing. After removing the barrel, the bolt and return spring are removed in a forward direction, completely dismantling the gun. Like the Sten, the Owen had a non-folding wire buttstock, but also had pistol grips like the Austen.^[15]

Two horseshoe magazines were constructed in the field, of 60 and 72 rounds. Little information exists as to the success of these experiments.^[16]

In 2004, an underground weapons factory was seized in Melbourne, Australia, yielding, among other things, three suppressed copies of the Owen submachine gun and parts to make six more. These had magazines inserted underneath rather than overhead, and were suspected of having been built for sale to local gangs involved in the illegal drug trade.^[17]

During Operation Ironside in 2021, an Owen submachine gun, magazines and ammunition suited for the firearm were found alongside a plastic fuel can containing petrol in a parkland on Gleeson Crescent at Rostrevor by STAR Group and Dog Operations Unit officers of the South Australia Police.^[18][19][20]

•  Australia^[21]
•  Indonesia^[22]
•  Laos^[23]
•  Netherlands^[24]
•  New Zealand^[25]
•  Rhodesia^[26][27]
•  United Kingdom^[28]

The gun received an Engineering Heritage National Marker from Engineers Australia as part of its Engineering Heritage Recognition Program.^[29]