The Soviet Union set up their factories to make things like Mosin Nagant rifles, SKS carbines, and AK-47s/AKMs/AK-74s, (along with heavier stuff) and simply go, go, GO. They made millions and millions, and sent them to every corner of their union, and to all their outlying puppet states -- and then sent the technology, including whole factories to those places as well, and told them go, go, GO!
The eastern bloc was very long on mass production and rugged reliability (with weapons at least) but very short on efficiency and inventory control.
If you get the chance, read C.J. Chivers'
The Gun. Tons of great info in there about this stuff. I don't have the book right to hand at the moment, but he cites one of the ex-eastern bloc countries (Bulgaria I think. Maybe it was Romania.) as conducting an inventory during the last decade to try and figure out how much of their military gear was still sitting around and hadn't been stolen and/or sold on the black market. At the time, even with all the losses, they had on hand
one hundred AKMs for every single soldier in their army.
Wow.
And that's just one type of weapon owned by one small satellite state of an enormous empire which produced enormous quantities of a bunch of different weapons. They literally filled up bunkers with cases of rifles, then closed the door and started filling up the next bunker, and so on.