Hi Mobryan
One thing to consider is that when the Russians began forming their artillery divisions they largely aquired the guns from current line divisions AFAIK. So the Russians had a very large artillery firepower at the point where they would launch an assault or to drop in front of a defensive position. However when on the advance or mounting a spontaneous counterattack for instance, They may in fact have had to use divisions whose artillery complements were less than standard.
Also without looking too far into it the artillery divisions tasks they may have been limited to pre-attack bombardment, defensive bombardments or similar. I say this as I believe Russian artillery divisions wern't integrated into the line divisions command and control structure but acted independantly.
This link describes the composition of one
http://books.google.com.au/books?id=...um=8&ct=result
Best Regards Chuck.