Here is a 9mm SMG made by Innovative Arms which was built primarily for testing the effectiveness of their suppressor designs on this type of weapon. Like many utilitarian tubeguns It fires from an open-bolt with a fairly high cyclic rate and also accepts 9mm British STEN magazines. It features a sturdy fixed skeleton stock, reminiscent of the folding stock of the Walther MPK. A pistol grip originally for the HK G3 has also been utilized.

Firing video: