There’s a story and hand drawn pictures on another forum. (http://www.newrhodesian.ca/)
The story is of a firefight, where the author/artist went through 5 (6?) 20 round magazines and the fight was still on.
He tells of reloading while trying to keep his head down and not get shot by communist terrorists.
Of how fumble fingered he suddenly was, loose rounds, how long it took to load one mag.

Planning on taking gear/food/ammo/other supplies off the enemy is planning for failure.
They may have had the same thought, and have nothing.
They may have used all their stuff.
They may be near home and brought nothing along, expecting to eat at home/camp that evening.
Talk about a rude awakening, ammo expended, lives risked and lost, and nothing gained.
Augmenting your supplies, adding to them, that’s one thing, but planning to gather what you need? Bad idea.

Here’s another viewpoint, what you may ‘get’ may be damaged, junk and covered with who knows what.
A few years ago, a two hour gunfight occurred in Nuevo Laredo just across the US/Mexico border.
Have a look at the gear that the cartels brought to the fight (ambush), what someone may be able to salvage, and the damage done both upon persons and materiel.

Note also, at least one person was trying to reload single rounds into magazines either because of running empty, damaged magazines or such. Note also the damaged (shot) magazines that were either in the ‘plate carriers’ or in weapons when damaged.

WARNING!! There is blood, gore and very explicit/graphic crime scene photos involved, if you do not want to see dead bodies, blood and such, please don’t open. And don’t say you weren’t warned.