It's one of a number of homemade weapons built by Chechen seperatists. These SMGs are collectively called Borz (Chechen for wolf).
There's a good page here showing the varied designs that all amount to the same thing - cheap to build, simple blowback, pistol-calibre automatic weapons.
https://homemadeguns.wordpress.com/2...bel-made-borz/
The wiki page has some detailed info
http://en.wikipedia.org/wiki/Borz