New weapons and animations can not be added. So carbines, DP-27 or mortars are out of the question. Between Shock Troopers and PPSH Cons, Soviets hardly need another CQC squad.
Another thing to remember is that this is just the first iteration. All units and abilities can still be changed based on feedback in the coming weeks.
There is no issues with their weapons, its their abilities is what not making any sense, smoke and sprint are useful for Shocks or PPSh cons, but not for 3xLMG squad.