i got the picture a few yrs go. i believe it is a russian prototype for use in trench warfare. they said it shot but the barrel only lasted 5-6 hundred rounds I think. too much friction, who would have thought.
mom's dad had a grease gun that worked the same way, and was used for cleaning krauts out of the danish streetscape. he said it was smoothbore, and of course, being a grease gun it was easy to replace the barrel.