 Despite advising that the gun could be upgraded to a larger calibre, Owen was told that the Australian Army would not be interested.Submachine guns, such as the Thompson Machine Gun, were regarded as being unimportant, and furthermore, there was a perception in the army that such weapons were for gangsters rather than soldiers.Owen, disappointed with the lack of interest in his firearm, enlisted in the Second Australian Imperial Force (AIF) in May 1940.