“ With thousands of SKS rifles in their inventory, the North Koreans reworked them into the SKS 84-M, which is more accurate than the AK-47 and mounts a scope. - In-game description”
The SKS is a Soviet semi-automatic carbine chambered for the 7.62×39mm round, designed in 1943 by Sergei Gavrilovich Simonov.
It is a gas-operated rifle that has a spring-loaded bolt carrier and a gas piston rod that work to unlock and cycle the action via gas pressure exerting pressure against them. The bolt is locked to contain the pressure of ignition at the moment of firing by tilting downwards at its rear and being held by a lug pressed into the receiver. At the moment of firing, the bolt carrier is pushed rearwards, which causes it to lift the bolt, unlocking it, and allowing it to be carried rearwards against a spring. This allows the fired case to be ejected and a new round from the magazine to be carried into the chamber.