Is your data per gun, or per unit?The Soviets tracked and reported their ammunition in the unit records by "basic loads". The basic load for some of the Soviet weapons are:
LMG ------------- 800
MMG ----------- 2,500
AAMG ---------- 2,000
SMG ------------- 300
50mm Mortar ----- 120
82mm Mortar ----- 120
76mm Div Gun ---- 140
76mm Rgt Gun ---- 140
122mm Howitzer --- 80
122mm Gun -------- 80
etc. (see pages 48 and 49 of the Final Report for the Kursk project).
Most of the units at Kursk carried around one plus basic loads of ammo with them at the start of the battle. For example, on 4 July, the 72nd Guards Rifle Division reports 1.08 ammo loads of Rifle rounds, 0.74 loads of AT rounds, 1.39 loads of 50mm Mortars, 1.38 loads of 82mm Mortars, 1.32 loads of 76mm Div Guns, 1.2 loads of 122mm guns, etc.
So if I had 12 122mm guns in my division, then the basic load would be 960 rounds. If the division had 20 or 24 76mm division guns, than the basic load is 2800 or 3360 rounds.