[priest39]

If you want it realistic, you'd up the drum mag to 71 rounds and the rate of fire to roughly 900 rounds per minute. Plus firing a round comparable to the MP-40.
In my realism mod, gave the Russian ppsh user two 71 rnd drums, (one on the gun and a spare,) and upped the ROF so that it fires 13 to 15 rounds per second. I also assigned the SVT sound to it to give it that nasty canvas ripping report. It's devastating at close to medium range, and fun to watch those unused to it waste all there ammo in the first few seconds.