Me: What happens if a soldier runs out of bullets? If so, are they allowed to use enemy bullets?
First, soldiers don’t run out of bullets, at least not in that sense. Factually speaking, if a soldier runs out of ammo, they cease being a fighter and becomes a target.
Soldiers don’t have an infinite supply of ammunition, but take careful actions to prevent this from ever happening. One, they never go into the fight alone. If shit hits the fan, they report their ammunition status during/after every engagement, both internally and to their headquarters.
Internal reports to the squad or platoon (or, even company). Two, they will cross level – share – ammunition so that everyone has about the same amount of ammo going into the next fight.
When the unit, or platoon reaches a certain threshold, say, down to 70%, they will request re-supply so that they get more ammo. In this case, not just ammo, but other vital elements – food, water, batteries, medicine, or anything else they need before it becomes a critical issue.
Three, a unit might change fighting tactics or shoot criteria to be more conservative in their usage rate. An unwritten rule for any discerning unit commander: Never get your troop formations over-extended while low on ammo!
And, well, if more shit hits the fan and the unit doesn’t have the luxury of those options, they will (attempt to) withdraw before they completely run out.
About using ammo (recovered) from the enemy, of course they can. Any ammunition from wounded or dead soldiers is shared among the rest, never left behind. Oh, but bodies or wounded fellows are never left behind, either.
There’s an issue on using enemy weapons. It has its OWN dangers – say, the sound of the gun, to the weapon’s maintenance (or lack of). If one of your platoons hear enemy fire, they will open fire on that position. Woe unto you, if YOU are using the enemy weapons – you’ll be getting friendly fire – and it’s usually riskier.
Also remember, using enemy weapons is a desperate last resort.
It means that not only has the unit collectively used nearly all of its ammunition, but that it also cannot effectively withdraw or obtain re-supply. It also means that the enemy they have been fighting has been so close that they could get their weapons – that may spell deadly losses on both sides.
Is that allowed?
Soldiers have to do a lot of things that aren’t “authorized” to get the mission done. It’s usually more about surviving the engagement, than ‘seeking permission’. By the time soldiers become NCOs, they usually develop a fine sense of where the line is between “taking initiative” and finding trouble.
In any case, if the situation was so dire that you were looking to scavenge an enemy weapon to survive the fight, no one would care about whether it was “authorized” or not.
Just stay alive, Goddammit!