>>64202514
This would actually work irl.
It's just an Uzi that fires blanks/wadding from a normal mag, which protects flachete from a barrel extension.
Flachette is too long to load in normal mags (see: spiw) so firing it like a rifle grenade makes sense.
Firing blanks the Uzi jamming wouldn't fuck it up, and you'd use an Uzi because you wanted a short barrel to accommodate that flachette extension, and the telescoping bolt is ideal for firing blanks because it will cycle easily.
Anything larger than 9mm, it would be hard to use with one hand, so the fast rate of fire compensates for that. Everything about it is short range.
You know I think if you loaded flachette in empty 410 cases and used a 410 mag and barrel extension, you could legitimately fire it from a regular gun with 9mm wadding. Ballistic performance very poor, but it would cycle, and fire