tfishell: Just wanted to say thanks to everyone who replied (or will reply :P). Admittedly, it was disappointing to hear the truth (as I thought I had found a cool, creative way out of the "random ammo not dropped by enemies"), but I'll just get it over it. ;) Thanks for the alternative weapon ideas, too. I guess as an American I'm a little pro-gun/self-defense biased, so I was hoping for a way to showcase an ordinary citizen defending his or herself (again, not looking for a debate, just saying) throughout a game against non-human enemies, but I guess really, learning to handle knives and other non-limited weaponry is a good idea, too. ;)
I'd also like to point out that giving weapons and ammunition more weight is nowhere near a bad thing. I.e, ammo could be scarce and only found in logical places, but it would also be realistically powerful (i.e, a single bullet can potentially kill or wound just about anything...short of an elephant, that is).
If it were me, though, I'd probably say "screw the realism," and do the reloading mechanic anyway. It's a great mechanic. It's the sort of thing that would convince me to buy the game. And after all, it's not any less plausible than the myriad of other superhuman things that videogame characters do.