Russian clone of a Finnish design.

A lot of it was the cartridge.
The 7.62 x 25 pistol cartridge was the magnum of its time, the most powerful pistol cartridge available.
An 85 grain bullet, 30 caliber, at 1,600 feet per second gave it an effective range of 150 meters(165 yards). The lighter bullet also made it more controllable. With the PPsH weighing eight pounds, it ought to be controllable.
good to 40 below zero without special lubricants. Ideal weapon for the Red Army’s peasant soldiers.
My Father’s battalion landed at Normandy, fought across Europe and was sent into Berlin not long after the Russians captured it. They were part of the “Army of Occupation”.
There was still occasional firing as a few holdouts, who Daddy described as SS Youth were killed.
I had just bought a Moisin Nagant and asked him if he ever saw them in action. He replied that he never saw a Russian carrying a bolt action. “They were all carrying those little sub machine guns.”