> Despite growing concern, Western officials said Russia's breakneck speed of actually using its military equipment is still outpacing its production levels: the country fired about 10 million rounds of artillery last year, but is on track to produce just two million rounds this year.

I've also heard that Russia has significant problems with guns, in addition to rounds. And shot-for-shot effectiveness of Russian artillery is several times less than the Ukrainian one. So I guess many factors are relevant here.