KS-23 Shotgun
The info from Modern Firearms suggests an introduction date for the military police and for MVD troops of the mid-1980s.
I know it's been mentioned before on the forum but the Modern Firearms site is really quite good for info on Soviet weapons as the site owner is Russian and a Russian Army reservist officer (if I remember correctly).
http://world.guns.ru/shotgun/rus/ks-23-e.html