... Including ones which are supposed to be realistic, the good character (who is supposed to be the most elite/battle experienced/street smart) will run out of ammo, proceed to pick up a new gun (often an AK-47 -- and often one of many lying around) off a dead enemy, but will never collect any extra magazines.

Usually, the formula goes, the character then proceeds to run out of ammo a few minutes later (this time far from the guns & magazines lying plentifully on the floor), and is captured/injured/put in a very tough spot, or has to run for his life.

I dont think Ive ever seen a character behave intelligently in this matter -- ever.