The PPSh-41 was also inspired by a weapon from Finland, but still the Soviet designer Spagin had to make a lot of adjustment. For example they used stamped part

The PPSh-41 was also inspired by a weapon from Finland, but still the Soviet designer Spagin had to make a lot of adjustment. For example they used stamped parts, in order to make it easier to produce the weapon in great numbers. Something similar must have happened with the AK-47 as well. https://en.wikipedia.org/wiki/PPSh-41 https://en.wikipedia.org/wiki/PPSh-41