Lack of unified ammunition in EU countries in reality is just slow transition process and in some cases exactly this helped Ukr a lot.
Because Ukr does have a lot of USSR era weapons.
With the same Poland, not likely they had supplied 290+60 tanks if these had 120 mm guns not 125 mm ....
+ these T-72 type also offered Ukr big bonus: Ujr does have 40+ years experience with them, therefore might had started to use immedately. Some spare parts and a lot of mechanics awailable etc.
Because Ukr does have a lot of USSR era weapons.
With the same Poland, not likely they had supplied 290+60 tanks if these had 120 mm guns not 125 mm ....
+ these T-72 type also offered Ukr big bonus: Ujr does have 40+ years experience with them, therefore might had started to use immedately. Some spare parts and a lot of mechanics awailable etc.