Let's dial back the size of weapons to submachine gun size. Umm. To the XL category of the submachine gun size. This is the Király smg which was named after it's constructor Király Pál, the model numbers: 1939M (basic), 1939/A M (folding stock), 1943M (folding stock and tilted magazine), K SMG (commie version from '50s).
What can be told this guy tells it:
https://youtube.com/watch?v=JWQFtRId85U [Embed]
Some stuff he misses out tho. For example the Hungarian military didn't adapted smgs because it was thought to be a weapon of policing force. Even for them they ordered some Bergmann and that's it.
In Hungarian it is sometimes referred as a machine carbine and not submachine gun.
I've different numbers on how many of these were manufactured: 8652 piece from the 1939M and 13176 from the 1943M (the army ordered 61350 piece).