Major factor with artillery is ability to commit counterbattery fire. Soviet artillery was bloody awful when it came to flexible firing methods (most artillery FO methods were right out of WW1) but this was overcome with very good artillery tactics (planning of use of guns). Complicated work, such as planning and counterbattery fire was concentrated on STAVKA formations while divisional artillery concentrated on direct support of infantry.
Counterbattery ratings should be based on following:
Corps and SHQ units (AR3 to 5).
Motorized units (AR 3)
Infantry (AR 2)
Second-line Infantry (AR 1)