This weapon is not as daft as it looks
The PPSh on single shot has a reasonable effective range, and its sniping capabilities in urban environments are well attested.
With the above scope, you could shoot accurately at 200-300m, which in an urban, or heavily foliated, or entrenched environment would be fine.
The scope would also add considerable advantages in low light conditions.
The gun also fires sub-sonic rounds, which are
much quieter, and could be silenced (rather than just supressed as with supersonic rounds).
The weight of the weapon combined with the relativley low power of the round reduces the recoil to virtually nothing when used to fire in semi automatic mode, making secondary/multiple target aquisition very easy, as well as the ability to effectively snipe at 'fleeting' targets.
Its not much different to having a Marlon or Rossi 30/30 or 38/357 with a scope on it, and plenty of people use them today.
So there.

Loosing your looks? Drink Vodka- it is much cheaper than Botox, & paralyses more muscles!
Kolya (Nikolai) Chuvashkin
Rank: Guards Mladshiy Serzhant