That doesn't classify it as a new type of gun. You can get an AS VAL folding skeleton stock and put it on a VSS.
Yes it does in the real world, it doesn't just work like in that example. There's more of a difference between the AS and the VSS than the stock, and just replacing the stock (for whatever reason you would anyway) wouldn't necessarily make it an AS. It's the same reason why the military doesn't just call the M4 or M4A1 the M16(A2) just because you could call it that with a shorter barrel. Designations are real and do matter.
