The Nagant pistols were intended (and typically) issued to officers. They also were used by a wide variety of soldiers, partisans and civilians. Not hard to imagine, considering number built was above 2.5 million units. The Nagant revolver was used extensively by the Russian Imperial Army and later by the Soviet Union after the Russian Revolution. In Russian service, it was known for its extreme sturdiness and ability to withstand abuse. Despite the advent of the more modern Soviet TT pistol, the M1895 remained in production and use throughout World War II.
There’s 7.62 ammunition, but no 7.62 rifle. He might be carrying extra ammo for the 7.62 gunner, spreading the load would make it easier to transport more ammo. Also the 7.62 ammunition was for the Mosin-Nagant rifle which was the most common rifle of the time (the Russians/Soviets made 37 million units of them). From the German grenades, the 7.62 ammo, and the 2 pistols and no ammo for the sub, probably he must have taken this picture after conducting a successful raid or attack.