[That means the Russians have held a massive superiority in supporting arms. As a former artillery officer myself, that’s an almost handicap to overcome, especially in the steppe areas of southern Ukraine.
Despite that, the attempted Russian mobile/tank advances have all failed. What has succeeded is the slog provided by simple weight of massive ordnance - their massive advantage in artillery and Air support, and grinding infantry asvance. But it is a rather pathetic commentary on their overall military effectiveness that it has taken them this long to accomplish even the limited gains they have.]
The Ukrainian problem is that they started the war with 1500 tubes of 152mm and up howitzers. They are running out of shells, and Ukrainian plants are presumably either not making enough to replace their stocks or not in working order, thanks to Russian missile attacks. In theory, they could rebore the tubes to 155mm. I gotta wonder how much time this takes, and whether the Ukrainians have the tooling and skilled personnel necessary to do this, due to Russian attacks on their industrial base.
They are getting limited supplies of 152mm, as at least one Romanian plant has spun up production, for Ukraine.