Dude, I dont know whether you understand WWII or not. But what is in RO1 related to PPSH is realistic, its not overpowered and it is just what it is in WWII. PPSH41 is famous for its much stronger fire power, much faster fire rate, and much better reliability than any other SMG in Germen Army at that time. And also drum is one of its most important factors for those features.
If you are one of those old RO1 players, I think you should understand that what we looking forward most from a game named Red Orchestra is called "reality", not balance first. Because in fact, WAR is some thing not balanced. Do you think it is balanced for a German soldier to fight against planty of US soldiers equipped with semi-auto M1 Garand by using his slow bolt action Kar 98k rifle in WWII? Absolutely not, but that was the reality, and that is what RO good at. If you really want a balance, why dont you ask TWI to remove MKb42 which is hardly can be seen at that time comparing to the huge amout of PPSH41 drum? And obviously you have much balanced choices for WWII games such as DOD: Source, BF: FH2 or CoD: WaW