I know wiki can be not the best source, but the article on UKR armed forces states:
'Ukraine and Nato estimate that 2.5 million tons of conventional ammunition were left in Ukraine as the Soviet military withdrew, as well as more than 7 million rifles, pistols, mortars, and machine guns. The surplus weapons and ammunition were stored in over 180 military bases, including in bunkers, salt mines and in the open. As of 2014, much of this surplus had not been scrapped.'