Why did Soviet soldiers, after several military operations in Afghanistan, threw out whole cartridges for their main weapon? There were a number of technical and convenience reasons for this. Let's explore what forced soldiers into this decision.
During the active firefight a lot of ammunition is lost due to natural causes - pouches rip, single rounds fall out of hand when reloading a magazine, faulty rounds ejected after stoppage.
In his book, "Under the southern sun", the author remembers how he was tasked to clean up the BTRs which have returned from the mission. These were his first weeks in Afghanistan, he just finished his initial training at the mainland Soviet Union. What he has seen inside the BTR was a complete shock. No, this was not the blood or dead bodies, but instead dozens of unused ammunitions of different nature - rifle and machine gun rounds, grenade primers, flares and smokes.
For him this was shocking as this was absolutely unacceptable in peacetime Soviet Army. Every single round was accounted for - soldiers had to collect and hand it all the empty cases after live firing training exercises. Leaving live ammunition unattended was totally corrupt and could leave for serious charges and military prison.
But for Afghnistan this was the norm, for obvious reasons. No one would collect ten-fifteen loose rounds, covered in dust and been stepped on to actually use it. Soviet army in Afghanistan never experienced any ammunition shortages, so instead of using old ammo, soldiers would just open fresh crates.
When Soviet soldiers went to the mountains, the most valuable thing they had to carry with them was the ammunition. For the AK-74 assault rifle, they took up to 1000 rounds of ammunition with them. Machin gunners would carry twice as much ammo. Not all rounds were loaded in magazines, in fact, majority was either stored in paper bags as they were supplied from the crates. Some were just poured into pockets and a duffel bag in bulk.
After several combat operations high in the mountains, most of the unused intact cartridges had to be thrown away. The thing is, they just fell into disrepair. The reason for this were harsh weather conditions - temperature extremes and high humidity. Here is what Dmitry Kleimenychev, a veteran Afghan, says:
The cartridges that I carried with me, I usually threw away after the operation. This was due to bad weather and because they were rubbed with quartz dust in a bag that I carried with me - they were covered with fine rust and could not be used.
Technical problems behind
Where did such a problem come from? The fact is that in the USSR the cartridge case was made of steel, which is subject to rusting. For comparison, most other countries produce their ammunition with brass cases, which do not corrode at the same level as regular steel.
In the early 1930s, the USSR mastered the production of steel liners clad with tombac (bimetal) instead of more expensive brass ones, and then the manufacture of liners from cold-rolled steel strip. Steel cased ammunition rusts really quickly when exposes to humid environment.
It was impossible to fire with rusted ammunition reliably. The weapon could just misfire. Therefore, soldiers threw them out. Since it was not difficult to get new ammunition and write off the old ones, combat units did just that. Obviously, it was not the rule. Some Soviet soldiers went through their entire service in Afghanistan and did not throw away a single cartridge (and some even didn't shoot a single round!)
Everything depended on the province in which the service took place, weather conditions, storage conditions for ammunition and the frequency of the combat exits themselves.