The Komsomolets was used by the Soviets, the Germans and Finland (captured vehicles). The Soviets and the Germans used a very similar looking AT gun: 37 mm Pak 36 (German) and 45 mm M1937 (Soviet) which was also used by Finnish forces. The main difference between the guns was the breech, which is hidden by one of the soldiers. The Finnish smg means propably, that it's the 45 mm gun.

sanitaeter said:

The Komsomolets was used by the Soviets, the Germans and Finland (captured vehicles). The Soviets and the Germans used a very similar looking AT gun: 37 mm Pak 36 (German) and 45 mm M1937 (Soviet) which was also used by Finnish forces. The main difference between the guns was the breech, which is hidden by one of the soldiers. The Finnish smg means propably, that it's the 45 mm gun.

Actually it's more likely it's a PaK 36 cannon; the PaK and M1937 were both used in some capacity by both the Soviets and Finns (Soviets produced the PaK on a license and Finns had PaKs given to them by Germany). The things standing out in the cannon that are making me lean more towards the PaK are the wheels (Soviets used spoked wheels for their M1937 carriages, while the PaK was predominantly on fully covered wheels) and the barrel shape (The M1937 has a noticeable drop in diameter, that would probably be visible even under the cloth cover. The PaK barrel, in comparison, is roughly the same diameter across the whole length).