Translation of Russian description: “7.62mm Pistol prototype. Power tape. Capacity of the tape 36 shots.” No manufacturer, designer or other explanation listed.
If I had to guess I’d probably say that the action is a blowback type where the rearward movement of the bolt mechanically advanced rounds in their chain-cylinders. Probably the bolt was manually cycled by gripping what looks to be textured portions of the bolt itself, although perhaps at one time some sort of gripping surface was also attached to that rod sticking out the back (I’m assuming it’s either attached directly to or just part of the bolt). With any luck the firearm featured automatic ejection from the side we can’t see. Hopefully the chain advanced from right to left so as to have minimized hot, recently fired chain contact with (a right handed) shooter’s hand. It looks as though it would have been very difficult to maintain a good solid lock-up between the chain chambers and the barrel, making accuracy poor.
I don’t have any reason to expect that the upper “chain gun” is in any way actually mechanically related to the select fire Tokarev test model below, however it is interesting to note the way in which firearms from the same country often take on a very similar outward appearance.