The scope is most probably mounted on picatinny rails; the little bugger a pretty ubiquitous these days. The rails would certainly continue under the mount, and the mount would be wider than the rails. Although I must say that the design is a bit of a chimera; an automatic weapon with a scope and a very short suppressor is…
When a cage is used the lowpoly vertex normals are ignored for projection and instead vertex will point towards their twin on the cage model. Since we want them all looking at the same tiny point in space we just shove the entire cage into that same spot. Scaling to 1% instead of 0% avoids bits of the cage getting merged…