Usually if you’re going to abandon equipment, you either booby trap it, or more likely render it forever unusable. (i.e. spike the barrel)
Also, you’d rig the ammo dump so you can blow it sky high at a time of your choosing, most likely remotey detonate it when the enemy has gathered around to see their “spoils” of war.
I find it hard to believe the Russians wouldn’t have done these things.
You booby trap if it is a controlled retreat. In the case of a panicked retreat you don’t