The AVT-40 and M14 are similar enough I think. The M14 man is using the correct stance (left leg forward, leaning heavily forward with the weapon firmly braced into the shoulder socket). The AVT-40 guy looks more casual.
Another similar weapon is the FG-42. About the same weight, size and cartridge.
FG42 firing - YouTube
Full Auto HK G3 - YouTube
These weapons have tremendous recoil when shot on full auto. Yes, large modern men with the correct posture can shoot short bursts properly. But most of the time it is totally impractical. The Soviet men of WWII were not quite as well fed or trained.
The AVT-40 is nothing like an assault rifle and cannot fulfill that role at all. It is like a full auto M1 Garand, or G3, or M14, with a low capacity magazine. It is a battle rifle, used with single shot setting 99% of the time. Variants where the full auto was meant to be used were the LMG variants - with heavier barrels, bipod and large capacity magazines - in essense, turning into something similar to the MG34 from the game but lighter weight.