The Owen Gun, which was known officially as the Owen Machine Carbine, was an Australian submachine gun designed by Evelyn (Evo) Owen in 1939. The Owen was the only entirely Australian-designed and main service submachine gun of World War II and was used by the Australian Army from 1943 until the mid-1960s.
https://en.wikipedia.org/wiki/Owen_Gun
Owen Gun: full disassembly & assembly
https://youtu.be/HwXcrN7HGXs
Don't try to recreate what you see in this video, as this is gameplay. This video was created using the game World of Guns:
http://store.steampowered.com/app/262410/
This game is also available on Google Play, App Store, Amazon and other platforms.