Looks like a MAK 7.62 X 39 with a butthole stock to me, its the foreshortening that makes the mag appear thinner, but still way to wide for 9mm.
To find the actual width, take the cosine of the angle between the rifle and the normal to the rifle, and divide that by the apparent width.
Roughly thats Cos 60/20mm = .5/20mm = 40mm