He is remarkably well equipped for the average partisan, he’s armed to the teeth: a PPSH-41 submachine gun, 1 RGD-33 grenade, 1 RPG-40 anti-tank grenade, 3 F1 grenades, a German Stielhandgranate 24, a belt of 7.62 ammunition and 2 M1895 Nagant pistols.
The Nagant pistols were intended (and typically) issued to officers they also found themselves in use by a wide variety of soldiers, partisans and civilians. Not hard to imagine, considering production from just two arsenals was above 2.5 million units.
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 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.