UPDATE on the artillery battle situation.
From Chervonets site
December 23, 14:30
The current fighting began early in the morning on December 18 with a serious artillery barrage. According to OSCE, the two sides have fired more than 700 howitzer shells. According to experts, this activity of the Ukrainian artillery is a a rarity. Gun barrels of majority of Ukrainian artillery pieces are worn, replacement barrels are not issued and Ukriane doesn't make them and there's no place to buy them. Already the Ukrainian forces feel ammunition shortage.
Note to self: Somewhere I have read some soldiers were killed and injured when a mortar round they were handling exploded, because it was old ammunition not just from Soviet times, but a batch of ammo that was surplus from the war.
Most recent ammunition is more than twenty years old, so I find it credible they are bringing out not just old pieces but old shells as well. Coupled with my estimates and other tidbits, it's quite likely the Ukrainian artillery is running low on ammo. Impossible to guess for how long they can go on, but when these telltale signs appear, the end is in sight, less than one year.
This item is further proof of the artillery war that has been going on unreported for the past two years, the wearing down of barrels confirms it, and explains a lot of things, why the Ukrainian artillery fire is weak , only a few shells per piece and they seem to be unable to make battery or larger salvos, nor intense or prolonged bombardments. Of couse other reasons are accurate and deadly Novorussian counterbattery fire, and scarcity of fuel and motor transport to bring the shells from the railheads to the pieces. But is clear that the pieces, intensely used during the battles of 2014 and early 2015 are worn, and can be used only sparingly.
If the barrels are worn that would also explain why there are no more shellings of civilian populations and destruction of Novorusssian frontline positions, simply, the cannon lose range and precision due to barrel wear, and since the Ukro artillery has been forced to pull back and fire from even longer ranges due to Novorussian counterbattery.
I have no professional trained eye, but it does struck me that most Ukrop artillery incoming fire tends to be weak and dispersed. Not the kind of concentrated barrages one has seen from world wars footage.