Ok, let's see if I can help …
Rucksack is below and under main chute, about where his butt is.
Special Weapons Bag[with ammo, grenades, demo, etc.] is over Rucksack and again below and under main chute. Weapons bag is released after exiting aircraft. Dangling on about a 15ft tether below the paratrooper.
Similar to the US but the US has our rucksack rigged under our reserve chute in front. On about a 17ft tether. Released when near the ground. Judging from looking at the horizon, etc.
A Rifle Bag is rigged behind the Soviet paratrooper's left shoulder, next to the main chute.
However Soviet paratroopers generally jump with AKD or AKS-74 Assault Rifle or similar and a few mags behind the reserve chute in front.
The Rifle Bag may carry heavier weapons, e.g. LMG, Sniper
Rifle, etc.
Osprey Soviet Bloc Elite Forces, pg. 57. Shows this, etc.