It was used by the Soviets during World War II as a infantry support machine gun and vehicle mounted weapon.
It is only used in Call of Duty: United Offensive as a vehicle mounted weapon. There are SG-43s on the T-34 tank, one mounted near the main cannon and one mounted on the top, and on Gaz-67b jeeps. It has the same stats as the mounted M1919. It is not seen being used by infantry, rather using MG-42s or DP-28s. You cannot use it as an infantry weapon, but must mount the vehicle. It has unlimited ammunition when mounted and uses a similar firing mechanism as the Browning M2.