Urrah!
Soviet small arms before the Cold War focused largely on their capability to be mass-produced with few concerns about precision machining. However, this meant that the Red Army could field enormous armies from every corner of the world and in any corner of the world. Field manuals, spare parts and gunsmiths with experience in these weapons are very easy to find. When performing any skill check regarding maintenance or repair of this weapon, add an Easy DM.
Papasha
The PPSh-41 was affectionately called "papasha" (or "daddy") by Soviet troops, owing to their appreciation of the weapon and how it kept them safe in bloody close quarters battles. This sentiment spread throughout the communist world as the Papasha was exported to every corner of the Earth, arming guerillas and red armies alike. When taking cover, instead of a Hard DM, add a Very Hard DM to the enemy's shots against this weapon's user.