Owen cleverly fashioned the drum magazine from an automobile crankshaft’s harmonic balancer. He drilled holes into the balancer to hold each individual cartridge, essentially creating a revolving cylinder with individual chambers. The magazine/cylinder held 44 .22 short cartridges.
The prototype lacked a traditional trigger. Instead, Owen added simple a thumb trigger that he made out of spring steel. When cocked, the trigger held the bolt back. Depressing the trigger released the bolt, allowing the weapon to slam-fire.
https://medium.com/war-is-boring/the-very-first-owen-gun-was-fashioned-from-car-parts-b69d231b92b6
It does look odd. I remember reading an Australian soldier’s account of one of the early battles. They described trading fire until they were ordered to fix bayonets. They started charging and he said the North Korean soldiers all threw down their weapons and ran away. From that point on the Australians relied heavily on bayonets as they knew the North Koreans were not too fond of them.